System and method for a gas turbine engine sensor

ABSTRACT

A system includes a gas turbine engine that includes a combustor section having a turbine combustor that generates combustion products, a turbine section having one or more turbine stages driven by the combustion products, an exhaust section disposed downstream of the turbine section, an oxygen sensor adaptor housing disposed in at least one of the combustor section, the turbine section, or the exhaust section, or any combination thereof, and an oxygen sensor disposed in the oxygen sensor adaptor housing. The oxygen sensor adaptor housing is configured to maintain a temperature of a portion of the oxygen sensor below an upper threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. ProvisionalPatent Application No. 61/860,217, entitled “SYSTEM AND METHOD FOR A GASTURBINE ENGINE SENSOR,” filed on Jul. 30, 2013, which is herebyincorporated by reference in its entirety for all purposes.

BACKGROUND

The subject matter disclosed herein relates to gas turbine engines, andmore specifically, to systems and methods for sensors of gas turbineengines.

Gas turbine engines are used in a wide variety of applications, such aspower generation, aircraft, and various machinery. Gas turbine enginesgenerally combust a fuel with an oxidant (e.g., air) in a combustorsection to generate hot combustion products, which then drive one ormore turbine stages of a turbine section. In turn, the turbine sectiondrives one or more compressor stages of a compressor section. Again, thefuel and oxidant mix in the combustor section, and then combust toproduce the hot combustion products. Gas turbine engines generallyinclude one or more sensors to detect various conditions within the gasturbine engine. Unfortunately, the high temperatures within the gasturbine engine can cause thermal stress and wear to the sensors and/ordecrease the longevity of the sensors. Furthermore, gas turbine enginestypically consume a vast amount of air as the oxidant, and output aconsiderable amount of exhaust gas into the atmosphere. In other words,the exhaust gas is typically wasted as a byproduct of the gas turbineoperation.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a gas turbine engine thatincludes a combustor section having a turbine combustor that generatescombustion products, a turbine section having one or more turbine stagesdriven by the combustion products, an exhaust section disposeddownstream of the turbine section, an oxygen sensor adaptor housingdisposed in at least one of the combustor section, the turbine section,or the exhaust section, or any combination thereof, and an oxygen sensordisposed in the oxygen sensor adaptor housing. The oxygen sensor adaptorhousing is configured to maintain a temperature of a portion of theoxygen sensor below an upper threshold.

In a second embodiment, a system includes an oxygen sensor adaptorhousing configured to mount in at least one of a combustor section of agas turbine engine, a turbine section of the gas turbine engine, or anexhaust section of the gas turbine engine, or any combination thereof,and an oxygen sensor disposed in the oxygen sensor adaptor housing. Theoxygen sensor adaptor housing is configured to maintain a temperature ofa portion of the oxygen sensor below an upper threshold.

In a third embodiment, a method includes combusting a fuel with anoxidant in a combustor section of a turbine combustor to generatecombustion products, driving a turbine of a turbine section with thecombustion products from the turbine combustor, expanding the combustionproducts from the turbine through an exhaust passage in an exhaustsection, sensing an oxygen concentration of the combustion productsusing an oxygen sensor disposed in an oxygen sensor adaptor housing thatis disposed in at least one of the combustor section, the turbinesection, or the exhaust section, or any combination thereof, andmaintaining a temperature of a portion of the oxygen sensor below anupper threshold using the oxygen sensor adaptor housing.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagram of an embodiment of a system having a turbine-basedservice system coupled to a hydrocarbon production system;

FIG. 2 is a diagram of an embodiment of the system of FIG. 1, furtherillustrating a control system and a combined cycle system;

FIG. 3 is a diagram of an embodiment of the system of FIGS. 1 and 2,further illustrating details of a gas turbine engine, exhaust gas supplysystem, and exhaust gas processing system;

FIG. 4 is a flow chart of an embodiment of a process for operating thesystem of FIGS. 1-3;

FIG. 5 is a schematic diagram of an embodiment of a gas turbine enginehaving a plurality of sensors, each having a sensor adaptor housing;

FIG. 6 is a schematic diagram of an embodiment of a sensor adaptorhousing;

FIG. 7 is a radial cross-sectional view of an embodiment of a gasturbine engine having a plurality of sensors each having a sensoradaptor housing;

FIG. 8 is a perspective view of a sensor (e.g., an oxygen sensor) thatmay be used with an embodiment of a sensor adaptor housing;

FIG. 9 is a graph of a signal characteristic curve of a sensor (e.g., anoxygen sensor) that may be used with an embodiment of a sensor adaptorhousing;

FIG. 10 is an axial side view of an embodiment of a sensor adaptorhousing;

FIG. 11 is an axial cross-sectional view of an embodiment of a sensoradaptor housing;

FIG. 12 is a partial cutaway perspective view of an embodiment of asensor adaptor housing;

FIG. 13 is a partial cutaway perspective view of an embodiment of asensor adaptor housing that may be used near a bottom of a gas turbineengine;

FIG. 14 is a partial cutaway perspective view of an embodiment of asensor adaptor housing with a coolant nozzle;

FIG. 15 is a partial cutaway perspective view of an embodiment of asensor adaptor housing with a coolant coil;

FIG. 16 is a radial cross-sectional view of an embodiment of a sensoradaptor housing; and

FIG. 17 is a radial cross-sectional view of an embodiment of a sensoradaptor housing with an airfoil-shaped cross-sectional shape.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in an engineering ordesign project, numerous implementation-specific decisions are made toachieve the specific goals, such as compliance with system-relatedand/or business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucheffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Detailed example embodiments are disclosed herein. However, specificstructural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments.Embodiments of the present invention may, however, be embodied in manyalternate forms, and should not be construed as limited to only theembodiments set forth herein.

Accordingly, while example embodiments are capable of variousmodifications and alternative forms, embodiments thereof are illustratedby way of example in the figures and will herein be described in detail.It should be understood, however, that there is no intent to limitexample embodiments to the particular forms disclosed, but to thecontrary, example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope of the presentinvention.

The terminology used herein is for describing particular embodimentsonly and is not intended to be limiting of example embodiments. As usedherein, the singular forms “a”, “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises”, “comprising”, “includes” and/or“including”, when used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

Although the terms first, second, primary, secondary, etc. may be usedherein to describe various elements, these elements should not belimited by these terms. These terms are only used to distinguish oneelement from another. For example, but not limiting to, a first elementcould be termed a second element, and, similarly, a second element couldbe termed a first element, without departing from the scope of exampleembodiments. As used herein, the term “and/or” includes any, and all,combinations of one or more of the associated listed items.

Certain terminology may be used herein for the convenience of the readeronly and is not to be taken as a limitation on the scope of theinvention. For example, words such as “upper”, “lower”, “left”, “right”,“front”, “rear”, “top”, “bottom”, “horizontal”, “vertical”, “upstream”,“downstream”, “fore”, “aft”, and the like; merely describe theconfiguration shown in the FIGS. Indeed, the element or elements of anembodiment of the present invention may be oriented in any direction andthe terminology, therefore, should be understood as encompassing suchvariations unless specified otherwise.

As discussed in detail below, the disclosed embodiments relate generallyto gas turbine systems with exhaust gas recirculation (EGR), andparticularly stoichiometric operation of the gas turbine systems usingEGR. For example, the gas turbine systems may be configured torecirculate the exhaust gas along an exhaust recirculation path,stoichiometrically combust fuel and oxidant along with at least some ofthe recirculated exhaust gas, and capture the exhaust gas for use invarious target systems. The recirculation of the exhaust gas along withstoichiometric combustion may help to increase the concentration levelof carbon dioxide (CO₂) in the exhaust gas, which can then be posttreated to separate and purify the CO₂ and nitrogen (N₂) for use invarious target systems. The gas turbine systems also may employ variousexhaust gas processing (e.g., heat recovery, catalyst reactions, etc.)along the exhaust recirculation path, thereby increasing theconcentration level of CO₂, reducing concentration levels of otheremissions (e.g., carbon monoxide, nitrogen oxides, and unburnthydrocarbons), and increasing energy recovery (e.g., with heat recoveryunits). Furthermore, the gas turbine engines may be configured tocombust the fuel and oxidant with one or more diffusion flames (e.g.,using diffusion fuel nozzles), premix flames (e.g., using premix fuelnozzles), or any combination thereof. In certain embodiments, thediffusion flames may help to maintain stability and operation withincertain limits for stoichiometric combustion, which in turn helps toincrease production of CO₂. For example, a gas turbine system operatingwith diffusion flames may enable a greater quantity of EGR, as comparedto a gas turbine system operating with premix flames. In turn, theincreased quantity of EGR helps to increase CO₂ production. Possibletarget systems include pipelines, storage tanks, carbon sequestrationsystems, and hydrocarbon production systems, such as enhanced oilrecovery (EOR) systems.

The disclosed embodiments provide systems and methods for sensors of gasturbine engines with EGR. Specifically, the gas turbine engine mayinclude a combustor section having a turbine combustor that generatescombustion products, a turbine section having one or more turbine stagesdriven by the combustion products, and an exhaust section disposeddownstream of the turbine section. A sensor adaptor housing, such as anoxygen sensor adaptor housing, may be disposed in at least one of thecombustor section, the turbine section, or the exhaust section, or anycombination thereof. A sensor (e.g., an oxygen sensor, a carbon monoxide(CO) sensor, a carbon dioxide (CO₂) sensor, a hydrogen (H₂) sensor, anitrogen oxides (NO_(X)) sensor, a sulfur oxides (SO_(X)) sensor, anunburnt fuel sensor, or any other gas composition sensor) may bedisposed in the sensor adaptor housing, which may maintain a temperatureof a portion (e.g., portion not directly in contact with the combustionproducts) of the sensor below a threshold (e.g., a maximum operatingtemperature limit). In certain embodiments, each sensor adaptor housingmay include 1, 2, 3, 4, 5, or more sensors. In some embodiments, othertypes of sensors, such as, but not limited to, temperature sensors,pressure sensors, flow rate sensors, flame sensors, optical sensors,composition sensors, and so forth, may be disposed in a sensor adaptorhousing. Each of these sensor adaptor housings may maintain atemperature of a portion of the sensor below a threshold. Although anytype of sensor may be used with the disclosed embodiments of sensoradaptor housings, the following discussion presents the sensor adaptorhousings in context of oxygen sensors as one possible example of thesensors.

By maintaining a temperature of the portion of the sensor (e.g., oxygensensor) below the threshold, the sensor may be protected from the hightemperatures associated with the gas turbine engine. Specifically,certain portions of the sensor (e.g., oxygen sensor) may have maximumoperating temperature limits less than the operating temperatures withinthe gas turbine engine. Thus, without using the sensor adaptor housing,these portions of the sensor (e.g., oxygen sensor) may be exposed totemperatures above their maximum operating temperature limits, therebypossibly causing thermal stress and wear and/or reduced life spans. Byusing the sensor adaptor housing, portions of the sensor (e.g., oxygensensor) may be operated below their maximum operating temperaturelimits, thereby increasing the longevity of the sensor. Although certainsensors (e.g., oxygen sensors) may have maximum operating temperaturelimits greater than the operating temperatures of the gas turbineengine, such sensors may be costly because of the expensive and/or rarematerials (e.g., high-temperature alloys) used to achieve the highmaximum operating temperature limits. Thus, less expensive sensors(e.g., oxygen sensors) with lower maximum operating temperature limitsmay be used with embodiments of the sensor adaptor housing describedbelow, thereby reducing the overall cost of the gas turbine engine.

FIG. 1 is a diagram of an embodiment of a system 10 having anhydrocarbon production system 12 associated with a turbine-based servicesystem 14. As discussed in further detail below, various embodiments ofthe turbine-based service system 14 are configured to provide variousservices, such as electrical power, mechanical power, and fluids (e.g.,exhaust gas), to the hydrocarbon production system 12 to facilitate theproduction or retrieval of oil and/or gas. In the illustratedembodiment, the hydrocarbon production system 12 includes an oil/gasextraction system 16 and an enhanced oil recovery (EOR) system 18, whichare coupled to a subterranean reservoir 20 (e.g., an oil, gas, orhydrocarbon reservoir). The oil/gas extraction system 16 includes avariety of surface equipment 22, such as a Christmas tree or productiontree 24, coupled to an oil/gas well 26. Furthermore, the well 26 mayinclude one or more tubulars 28 extending through a drilled bore 30 inthe earth 32 to the subterranean reservoir 20. The tree 24 includes oneor more valves, chokes, isolation sleeves, blowout preventers, andvarious flow control devices, which regulate pressures and control flowsto and from the subterranean reservoir 20. While the tree 24 isgenerally used to control the flow of the production fluid (e.g., oil orgas) out of the subterranean reservoir 20, the EOR system 18 mayincrease the production of oil or gas by injecting one or more fluidsinto the subterranean reservoir 20.

Accordingly, the EOR system 18 may include a fluid injection system 34,which has one or more tubulars 36 extending through a bore 38 in theearth 32 to the subterranean reservoir 20. For example, the EOR system18 may route one or more fluids 40, such as gas, steam, water,chemicals, or any combination thereof, into the fluid injection system34. For example, as discussed in further detail below, the EOR system 18may be coupled to the turbine-based service system 14, such that thesystem 14 routes an exhaust gas 42 (e.g., substantially or entirely freeof oxygen) to the EOR system 18 for use as the injection fluid 40. Thefluid injection system 34 routes the fluid 40 (e.g., the exhaust gas 42)through the one or more tubulars 36 into the subterranean reservoir 20,as indicated by arrows 44. The injection fluid 40 enters thesubterranean reservoir 20 through the tubular 36 at an offset distance46 away from the tubular 28 of the oil/gas well 26. Accordingly, theinjection fluid 40 displaces the oil/gas 48 disposed in the subterraneanreservoir 20, and drives the oil/gas 48 up through the one or moretubulars 28 of the hydrocarbon production system 12, as indicated byarrows 50. As discussed in further detail below, the injection fluid 40may include the exhaust gas 42 originating from the turbine-basedservice system 14, which is able to generate the exhaust gas 42 on-siteas needed by the hydrocarbon production system 12. In other words, theturbine-based system 14 may simultaneously generate one or more services(e.g., electrical power, mechanical power, steam, water (e.g.,desalinated water), and exhaust gas (e.g., substantially free ofoxygen)) for use by the hydrocarbon production system 12, therebyreducing or eliminating the reliance on external sources of suchservices.

In the illustrated embodiment, the turbine-based service system 14includes a stoichiometric exhaust gas recirculation (SEGR) gas turbinesystem 52 and an exhaust gas (EG) processing system 54. The gas turbinesystem 52 may be configured to operate in a stoichiometric combustionmode of operation (e.g., a stoichiometric control mode) and anon-stoichiometric combustion mode of operation (e.g., anon-stoichiometric control mode), such as a fuel-lean control mode or afuel-rich control mode. In the stoichiometric control mode, thecombustion generally occurs in a substantially stoichiometric ratio of afuel and oxidant, thereby resulting in substantially stoichiometriccombustion. In particular, stoichiometric combustion generally involvesconsuming substantially all of the fuel and oxidant in the combustionreaction, such that the products of combustion are substantially orentirely free of unburnt fuel and oxidant. One measure of stoichiometriccombustion is the equivalence ratio, or phi (φ), which is the ratio ofthe actual fuel/oxidant ratio relative to the stoichiometricfuel/oxidant ratio. An equivalence ratio of greater than 1.0 results ina fuel-rich combustion of the fuel and oxidant, whereas an equivalenceratio of less than 1.0 results in a fuel-lean combustion of the fuel andoxidant. In contrast, an equivalence ratio of 1.0 results in combustionthat is neither fuel-rich nor fuel-lean, thereby substantially consumingall of the fuel and oxidant in the combustion reaction. In context ofthe disclosed embodiments, the term stoichiometric or substantiallystoichiometric may refer to an equivalence ratio of approximately 0.95to approximately 1.05. However, the disclosed embodiments may alsoinclude an equivalence ratio of 1.0 plus or minus 0.01, 0.02, 0.03,0.04, 0.05, or more. Again, the stoichiometric combustion of fuel andoxidant in the turbine-based service system 14 may result in products ofcombustion or exhaust gas (e.g., 42) with substantially no unburnt fuelor oxidant remaining. For example, the exhaust gas 42 may have less than1, 2, 3, 4, or 5 percent by volume of oxidant (e.g., oxygen), unburntfuel or hydrocarbons (e.g., HCs), nitrogen oxides (e.g., NO_(X)), carbonmonoxide (CO), sulfur oxides (e.g., SO_(X)), hydrogen, and otherproducts of incomplete combustion. By further example, the exhaust gas42 may have less than approximately 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 200, 300, 400, 500, 1000, 2000, 3000, 4000, or 5000 parts permillion by volume (ppmv) of oxidant (e.g., oxygen), unburnt fuel orhydrocarbons (e.g., HCs), nitrogen oxides (e.g., NO_(X)), carbonmonoxide (CO), sulfur oxides (e.g., SO_(X)), hydrogen, and otherproducts of incomplete combustion. However, the disclosed embodimentsalso may produce other ranges of residual fuel, oxidant, and otheremissions levels in the exhaust gas 42. As used herein, the termsemissions, emissions levels, and emissions targets may refer toconcentration levels of certain products of combustion (e.g., NO_(X),CO, SO_(X), O₂, N₂, H₂, HCs, etc.), which may be present in recirculatedgas streams, vented gas streams (e.g., exhausted into the atmosphere),and gas streams used in various target systems (e.g., the hydrocarbonproduction system 12).

Although the SEGR gas turbine system 52 and the EG processing system 54may include a variety of components in different embodiments, theillustrated EG processing system 54 includes a heat recovery steamgenerator (HRSG) 56 and an exhaust gas recirculation (EGR) system 58,which receive and process an exhaust gas 60 originating from the SEGRgas turbine system 52. The HRSG 56 may include one or more heatexchangers, condensers, and various heat recovery equipment, whichcollectively function to transfer heat from the exhaust gas 60 to astream of water, thereby generating steam 62. The steam 62 may be usedin one or more steam turbines, the EOR system 18, or any other portionof the hydrocarbon production system 12. For example, the HRSG 56 maygenerate low pressure, medium pressure, and/or high pressure steam 62,which may be selectively applied to low, medium, and high pressure steamturbine stages, or different applications of the EOR system 18. Inaddition to the steam 62, a treated water 64, such as a desalinatedwater, may be generated by the HRSG 56, the EGR system 58, and/oranother portion of the EG processing system 54 or the SEGR gas turbinesystem 52. The treated water 64 (e.g., desalinated water) may beparticularly useful in areas with water shortages, such as inland ordesert regions. The treated water 64 may be generated, at least in part,due to the large volume of air driving combustion of fuel within theSEGR gas turbine system 52. While the on-site generation of steam 62 andwater 64 may be beneficial in many applications (including thehydrocarbon production system 12), the on-site generation of exhaust gas42, 60 may be particularly beneficial for the EOR system 18, due to itslow oxygen content, high pressure, and heat derived from the SEGR gasturbine system 52. Accordingly, the HRSG 56, the EGR system 58, and/oranother portion of the EG processing system 54 may output or recirculatean exhaust gas 66 into the SEGR gas turbine system 52, while alsorouting the exhaust gas 42 to the EOR system 18 for use with thehydrocarbon production system 12. Likewise, the exhaust gas 42 may beextracted directly from the SEGR gas turbine system 52 (i.e., withoutpassing through the EG processing system 54) for use in the EOR system18 of the hydrocarbon production system 12.

The exhaust gas recirculation is handled by the EGR system 58 of the EGprocessing system 54. For example, the EGR system 58 includes one ormore conduits, valves, blowers, exhaust gas treatment systems (e.g.,filters, particulate removal units, gas separation units, gaspurification units, heat exchangers, heat recovery units, moistureremoval units, catalyst units, chemical injection units, or anycombination thereof), and controls to recirculate the exhaust gas alongan exhaust gas circulation path from an output (e.g., discharged exhaustgas 60) to an input (e.g., intake exhaust gas 66) of the SEGR gasturbine system 52. In the illustrated embodiment, the SEGR gas turbinesystem 52 intakes the exhaust gas 66 into a compressor section havingone or more compressors, thereby compressing the exhaust gas 66 for usein a combustor section along with an intake of an oxidant 68 and one ormore fuels 70. The oxidant 68 may include ambient air, pure oxygen,oxygen-enriched air, oxygen-reduced air, oxygen-nitrogen mixtures, orany suitable oxidant that facilitates combustion of the fuel 70. Thefuel 70 may include one or more gas fuels, liquid fuels, or anycombination thereof. For example, the fuel 70 may include natural gas,liquefied natural gas (LNG), syngas, methane, ethane, propane, butane,naphtha, kerosene, diesel fuel, ethanol, methanol, biofuel, or anycombination thereof.

The SEGR gas turbine system 52 mixes and combusts the exhaust gas 66,the oxidant 68, and the fuel 70 in the combustor section, therebygenerating hot combustion gases or exhaust gas 60 to drive one or moreturbine stages in a turbine section. In certain embodiments, eachcombustor in the combustor section includes one or more premix fuelnozzles, one or more diffusion fuel nozzles, or any combination thereof.For example, each premix fuel nozzle may be configured to mix theoxidant 68 and the fuel 70 internally within the fuel nozzle and/orpartially upstream of the fuel nozzle, thereby injecting an oxidant-fuelmixture from the fuel nozzle into the combustion zone for a premixedcombustion (e.g., a premixed flame). By further example, each diffusionfuel nozzle may be configured to isolate the flows of oxidant 68 andfuel 70 within the fuel nozzle, thereby separately injecting the oxidant68 and the fuel 70 from the fuel nozzle into the combustion zone fordiffusion combustion (e.g., a diffusion flame). In particular, thediffusion combustion provided by the diffusion fuel nozzles delaysmixing of the oxidant 68 and the fuel 70 until the point of initialcombustion, i.e., the flame region. In embodiments employing thediffusion fuel nozzles, the diffusion flame may provide increased flamestability, because the diffusion flame generally forms at the point ofstoichiometry between the separate streams of oxidant 68 and fuel 70(i.e., as the oxidant 68 and fuel 70 are mixing). In certainembodiments, one or more diluents (e.g., the exhaust gas 60, steam,nitrogen, or another inert gas) may be pre-mixed with the oxidant 68,the fuel 70, or both, in either the diffusion fuel nozzle or the premixfuel nozzle. In addition, one or more diluents (e.g., the exhaust gas60, steam, nitrogen, or another inert gas) may be injected into thecombustor at or downstream from the point of combustion within eachcombustor. The use of these diluents may help temper the flame (e.g.,premix flame or diffusion flame), thereby helping to reduce NO_(X)emissions, such as nitrogen monoxide (NO) and nitrogen dioxide (NO₂).Regardless of the type of flame, the combustion produces hot combustiongases or exhaust gas 60 to drive one or more turbine stages. As eachturbine stage is driven by the exhaust gas 60, the SEGR gas turbinesystem 52 generates a mechanical power 72 and/or an electrical power 74(e.g., via an electrical generator). The system 52 also outputs theexhaust gas 60, and may further output water 64. Again, the water 64 maybe a treated water, such as a desalinated water, which may be useful ina variety of applications on-site or off-site.

Exhaust extraction is also provided by the SEGR gas turbine system 52using one or more extraction points 76. For example, the illustratedembodiment includes an exhaust gas (EG) supply system 78 having anexhaust gas (EG) extraction system 80 and an exhaust gas (EG) treatmentsystem 82, which receive exhaust gas 42 from the extraction points 76,treat the exhaust gas 42, and then supply or distribute the exhaust gas42 to various target systems. The target systems may include the EORsystem 18 and/or other systems, such as a pipeline 86, a storage tank88, or a carbon sequestration system 90. The EG extraction system 80 mayinclude one or more conduits, valves, controls, and flow separations,which facilitate isolation of the exhaust gas 42 from the oxidant 68,the fuel 70, and other contaminants, while also controlling thetemperature, pressure, and flow rate of the extracted exhaust gas 42.The EG treatment system 82 may include one or more heat exchangers(e.g., heat recovery units such as heat recovery steam generators,condensers, coolers, or heaters), catalyst systems (e.g., oxidationcatalyst systems), particulate and/or water removal systems (e.g., gasdehydration units, inertial separators, coalescing filters, waterimpermeable filters, and other filters), chemical injection systems,solvent based treatment systems (e.g., absorbers, flash tanks, etc.),carbon capture systems, gas separation systems, gas purificationsystems, and/or a solvent based treatment system, exhaust gascompressors, any combination thereof. These subsystems of the EGtreatment system 82 enable control of the temperature, pressure, flowrate, moisture content (e.g., amount of water removal), particulatecontent (e.g., amount of particulate removal), and gas composition(e.g., percentage of CO₂, N₂, etc.).

The extracted exhaust gas 42 is treated by one or more subsystems of theEG treatment system 82, depending on the target system. For example, theEG treatment system 82 may direct all or part of the exhaust gas 42through a carbon capture system, a gas separation system, a gaspurification system, and/or a solvent based treatment system, which iscontrolled to separate and purify a carbonaceous gas (e.g., carbondioxide) 92 and/or nitrogen (N₂) 94 for use in the various targetsystems. For example, embodiments of the EG treatment system 82 mayperform gas separation and purification to produce a plurality ofdifferent streams 95 of exhaust gas 42, such as a first stream 96, asecond stream 97, and a third stream 98. The first stream 96 may have afirst composition that is rich in carbon dioxide and/or lean in nitrogen(e.g., a CO₂ rich, N₂ lean stream). The second stream 97 may have asecond composition that has intermediate concentration levels of carbondioxide and/or nitrogen (e.g., intermediate concentration CO₂, N₂stream). The third stream 98 may have a third composition that is leanin carbon dioxide and/or rich in nitrogen (e.g., a CO₂ lean, N₂ richstream). Each stream 95 (e.g., 96, 97, and 98) may include a gasdehydration unit, a filter, a gas compressor, or any combinationthereof, to facilitate delivery of the stream 95 to a target system. Incertain embodiments, the CO₂ rich, N₂ lean stream 96 may have a CO₂purity or concentration level of greater than approximately 70, 75, 80,85, 90, 95, 96, 97, 98, or 99 percent by volume, and a N₂ purity orconcentration level of less than approximately 1, 2, 3, 4, 5, 10, 15,20, 25, or 30 percent by volume. In contrast, the CO₂ lean, N₂ richstream 98 may have a CO₂ purity or concentration level of less thanapproximately 1, 2, 3, 4, 5, 10, 15, 20, 25, or 30 percent by volume,and a N₂ purity or concentration level of greater than approximately 70,75, 80, 85, 90, 95, 96, 97, 98, or 99 percent by volume. Theintermediate concentration CO₂, N₂ stream 97 may have a CO₂ purity orconcentration level and/or a N₂ purity or concentration level of betweenapproximately 30 to 70, 35 to 65, 40 to 60, or 45 to 55 percent byvolume. Although the foregoing ranges are merely non-limiting examples,the CO₂ rich, N₂ lean stream 96 and the CO₂ lean, N₂ rich stream 98 maybe particularly well suited for use with the EOR system 18 and the othersystems 84. However, any of these rich, lean, or intermediateconcentration CO₂ streams 95 may be used, alone or in variouscombinations, with the EOR system 18 and the other systems 84. Forexample, the EOR system 18 and the other systems 84 (e.g., the pipeline86, storage tank 88, and the carbon sequestration system 90) each mayreceive one or more CO₂ rich, N₂ lean streams 96, one or more CO₂ lean,N₂ rich streams 98, one or more intermediate concentration CO₂, N₂streams 97, and one or more untreated exhaust gas 42 streams (i.e.,bypassing the EG treatment system 82).

The EG extraction system 80 extracts the exhaust gas 42 at one or moreextraction points 76 along the compressor section, the combustorsection, and/or the turbine section, such that the exhaust gas 42 may beused in the EOR system 18 and other systems 84 at suitable temperaturesand pressures. The EG extraction system 80 and/or the EG treatmentsystem 82 also may circulate fluid flows (e.g., exhaust gas 42) to andfrom the EG processing system 54. For example, a portion of the exhaustgas 42 passing through the EG processing system 54 may be extracted bythe EG extraction system 80 for use in the EOR system 18 and the othersystems 84. In certain embodiments, the EG supply system 78 and the EGprocessing system 54 may be independent or integral with one another,and thus may use independent or common subsystems. For example, the EGtreatment system 82 may be used by both the EG supply system 78 and theEG processing system 54. Exhaust gas 42 extracted from the EG processingsystem 54 may undergo multiple stages of gas treatment, such as one ormore stages of gas treatment in the EG processing system 54 followed byone or more additional stages of gas treatment in the EG treatmentsystem 82.

At each extraction point 76, the extracted exhaust gas 42 may besubstantially free of oxidant 68 and fuel 70 (e.g., unburnt fuel orhydrocarbons) due to substantially stoichiometric combustion and/or gastreatment in the EG processing system 54. Furthermore, depending on thetarget system, the extracted exhaust gas 42 may undergo furthertreatment in the EG treatment system 82 of the EG supply system 78,thereby further reducing any residual oxidant 68, fuel 70, or otherundesirable products of combustion. For example, either before or aftertreatment in the EG treatment system 82, the extracted exhaust gas 42may have less than 1, 2, 3, 4, or 5 percent by volume of oxidant (e.g.,oxygen), unburnt fuel or hydrocarbons (e.g., HCs), nitrogen oxides(e.g., NO_(X)), carbon monoxide (CO), sulfur oxides (e.g., SO_(X)),hydrogen, and other products of incomplete combustion. By furtherexample, either before or after treatment in the EG treatment system 82,the extracted exhaust gas 42 may have less than approximately 10, 20,30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 1000, 2000, 3000,4000, or 5000 parts per million by volume (ppmv) of oxidant (e.g.,oxygen), unburnt fuel or hydrocarbons (e.g., HCs), nitrogen oxides(e.g., NO_(X)), carbon monoxide (CO), sulfur oxides (e.g., SO_(X)),hydrogen, and other products of incomplete combustion. Thus, the exhaustgas 42 is particularly well suited for use with the EOR system 18.

The EGR operation of the turbine system 52 specifically enables theexhaust extraction at a multitude of locations 76. For example, thecompressor section of the system 52 may be used to compress the exhaustgas 66 without any oxidant 68 (i.e., only compression of the exhaust gas66), such that a substantially oxygen-free exhaust gas 42 may beextracted from the compressor section and/or the combustor section priorto entry of the oxidant 68 and the fuel 70. The extraction points 76 maybe located at interstage ports between adjacent compressor stages, atports along the compressor discharge casing, at ports along eachcombustor in the combustor section, or any combination thereof. Incertain embodiments, the exhaust gas 66 may not mix with the oxidant 68and fuel 70 until it reaches the head end portion and/or fuel nozzles ofeach combustor in the combustor section. Furthermore, one or more flowseparators (e.g., walls, dividers, baffles, or the like) may be used toisolate the oxidant 68 and the fuel 70 from the extraction points 76.With these flow separators, the extraction points 76 may be disposeddirectly along a wall of each combustor in the combustor section.

Once the exhaust gas 66, oxidant 68, and fuel 70 flow through the headend portion (e.g., through fuel nozzles) into the combustion portion(e.g., combustion chamber) of each combustor, the SEGR gas turbinesystem 52 is controlled to provide a substantially stoichiometriccombustion of the exhaust gas 66, oxidant 68, and fuel 70. For example,the system 52 may maintain an equivalence ratio of approximately 0.95 toapproximately 1.05. As a result, the products of combustion of themixture of exhaust gas 66, oxidant 68, and fuel 70 in each combustor issubstantially free of oxygen and unburnt fuel. Thus, the products ofcombustion (or exhaust gas) may be extracted from the turbine section ofthe SEGR gas turbine system 52 for use as the exhaust gas 42 routed tothe EOR system 18. Along the turbine section, the extraction points 76may be located at any turbine stage, such as interstage ports betweenadjacent turbine stages. Thus, using any of the foregoing extractionpoints 76, the turbine-based service system 14 may generate, extract,and deliver the exhaust gas 42 to the hydrocarbon production system 12(e.g., the EOR system 18) for use in the production of oil/gas 48 fromthe subterranean reservoir 20.

FIG. 2 is a diagram of an embodiment of the system 10 of FIG. 1,illustrating a control system 100 coupled to the turbine-based servicesystem 14 and the hydrocarbon production system 12. In the illustratedembodiment, the turbine-based service system 14 includes a combinedcycle system 102, which includes the SEGR gas turbine system 52 as atopping cycle, a steam turbine 104 as a bottoming cycle, and the HRSG 56to recover heat from the exhaust gas 60 to generate the steam 62 fordriving the steam turbine 104. Again, the SEGR gas turbine system 52receives, mixes, and stoichiometrically combusts the exhaust gas 66, theoxidant 68, and the fuel 70 (e.g., premix and/or diffusion flames),thereby producing the exhaust gas 60, the mechanical power 72, theelectrical power 74, and/or the water 64. For example, the SEGR gasturbine system 52 may drive one or more loads or machinery 106, such asan electrical generator, an oxidant compressor (e.g., a main aircompressor), a gear box, a pump, equipment of the hydrocarbon productionsystem 12, or any combination thereof. In some embodiments, themachinery 106 may include other drives, such as electrical motors orsteam turbines (e.g., the steam turbine 104), in tandem with the SEGRgas turbine system 52. Accordingly, an output of the machinery 106driven by the SEGR gas turbines system 52 (and any additional drives)may include the mechanical power 72 and the electrical power 74. Themechanical power 72 and/or the electrical power 74 may be used on-sitefor powering the hydrocarbon production system 12, the electrical power74 may be distributed to the power grid, or any combination thereof. Theoutput of the machinery 106 also may include a compressed fluid, such asa compressed oxidant 68 (e.g., air or oxygen), for intake into thecombustion section of the SEGR gas turbine system 52. Each of theseoutputs (e.g., the exhaust gas 60, the mechanical power 72, theelectrical power 74, and/or the water 64) may be considered a service ofthe turbine-based service system 14.

The SEGR gas turbine system 52 produces the exhaust gas 42, 60, whichmay be substantially free of oxygen, and routes this exhaust gas 42, 60to the EG processing system 54 and/or the EG supply system 78. The EGsupply system 78 may treat and delivery the exhaust gas 42 (e.g.,streams 95) to the hydrocarbon production system 12 and/or the othersystems 84. As discussed above, the EG processing system 54 may includethe HRSG 56 and the EGR system 58. The HRSG 56 may include one or moreheat exchangers, condensers, and various heat recovery equipment, whichmay be used to recover or transfer heat from the exhaust gas 60 to water108 to generate the steam 62 for driving the steam turbine 104. Similarto the SEGR gas turbine system 52, the steam turbine 104 may drive oneor more loads or machinery 106, thereby generating the mechanical power72 and the electrical power 74. In the illustrated embodiment, the SEGRgas turbine system 52 and the steam turbine 104 are arranged in tandemto drive the same machinery 106. However, in other embodiments, the SEGRgas turbine system 52 and the steam turbine 104 may separately drivedifferent machinery 106 to independently generate mechanical power 72and/or electrical power 74. As the steam turbine 104 is driven by thesteam 62 from the HRSG 56, the steam 62 gradually decreases intemperature and pressure. Accordingly, the steam turbine 104recirculates the used steam 62 and/or water 108 back into the HRSG 56for additional steam generation via heat recovery from the exhaust gas60. In addition to steam generation, the HRSG 56, the EGR system 58,and/or another portion of the EG processing system 54 may produce thewater 64, the exhaust gas 42 for use with the hydrocarbon productionsystem 12, and the exhaust gas 66 for use as an input into the SEGR gasturbine system 52. For example, the water 64 may be a treated water 64,such as a desalinated water for use in other applications. Thedesalinated water may be particularly useful in regions of low wateravailability. Regarding the exhaust gas 60, embodiments of the EGprocessing system 54 may be configured to recirculate the exhaust gas 60through the EGR system 58 with or without passing the exhaust gas 60through the HRSG 56.

In the illustrated embodiment, the SEGR gas turbine system 52 has anexhaust recirculation path 110, which extends from an exhaust outlet toan exhaust inlet of the system 52. Along the path 110, the exhaust gas60 passes through the EG processing system 54, which includes the HRSG56 and the EGR system 58 in the illustrated embodiment. The EGR system58 may include one or more conduits, valves, blowers, gas treatmentsystems (e.g., filters, particulate removal units, gas separation units,gas purification units, heat exchangers, heat recovery units such asheat recovery steam generators, moisture removal units, catalyst units,chemical injection units, or any combination thereof) in series and/orparallel arrangements along the path 110. In other words, the EGR system58 may include any flow control components, pressure control components,temperature control components, moisture control components, and gascomposition control components along the exhaust recirculation path 110between the exhaust outlet and the exhaust inlet of the system 52.Accordingly, in embodiments with the HRSG 56 along the path 110, theHRSG 56 may be considered a component of the EGR system 58. However, incertain embodiments, the HRSG 56 may be disposed along an exhaust pathindependent from the exhaust recirculation path 110. Regardless ofwhether the HRSG 56 is along a separate path or a common path with theEGR system 58, the HRSG 56 and the EGR system 58 intake the exhaust gas60 and output either the recirculated exhaust gas 66, the exhaust gas 42for use with the EG supply system 78 (e.g., for the hydrocarbonproduction system 12 and/or other systems 84), or another output ofexhaust gas. Again, the SEGR gas turbine system 52 intakes, mixes, andstoichiometrically combusts the exhaust gas 66, the oxidant 68, and thefuel 70 (e.g., premixed and/or diffusion flames) to produce asubstantially oxygen-free and fuel-free exhaust gas 60 for distributionto the EG processing system 54, the hydrocarbon production system 12, orother systems 84.

As noted above with reference to FIG. 1, the hydrocarbon productionsystem 12 may include a variety of equipment to facilitate the recoveryor production of oil/gas 48 from a subterranean reservoir 20 through anoil/gas well 26. For example, the hydrocarbon production system 12 mayinclude the EOR system 18 having the fluid injection system 34. In theillustrated embodiment, the fluid injection system 34 includes anexhaust gas injection EOR system 112 and a steam injection EOR system114. Although the fluid injection system 34 may receive fluids from avariety of sources, the illustrated embodiment may receive the exhaustgas 42 and the steam 62 from the turbine-based service system 14. Theexhaust gas 42 and/or the steam 62 produced by the turbine-based servicesystem 14 also may be routed to the hydrocarbon production system 12 foruse in other oil/gas systems 116.

The quantity, quality, and flow of the exhaust gas 42 and/or the steam62 may be controlled by the control system 100. The control system 100may be dedicated entirely to the turbine-based service system 14, or thecontrol system 100 may optionally also provide control (or at least somedata to facilitate control) for the hydrocarbon production system 12and/or other systems 84. In the illustrated embodiment, the controlsystem 100 includes a controller 118 having a processor 120, a memory122, a steam turbine control 124, a SEGR gas turbine system control 126,and a machinery control 128. The processor 120 may include a singleprocessor or two or more redundant processors, such as triple redundantprocessors for control of the turbine-based service system 14. Thememory 122 may include volatile and/or non-volatile memory. For example,the memory 122 may include one or more hard drives, flash memory,read-only memory, random access memory, or any combination thereof. Thecontrols 124, 126, and 128 may include software and/or hardwarecontrols. For example, the controls 124, 126, and 128 may includevarious instructions or code stored on the memory 122 and executable bythe processor 120. The control 124 is configured to control operation ofthe steam turbine 104, the SEGR gas turbine system control 126 isconfigured to control the system 52, and the machinery control 128 isconfigured to control the machinery 106. Thus, the controller 118 (e.g.,controls 124, 126, and 128) may be configured to coordinate varioussub-systems of the turbine-based service system 14 to provide a suitablestream of the exhaust gas 42 to the hydrocarbon production system 12.

In certain embodiments of the control system 100, each element (e.g.,system, subsystem, and component) illustrated in the drawings ordescribed herein includes (e.g., directly within, upstream, ordownstream of such element) one or more industrial control features,such as sensors and control devices, which are communicatively coupledwith one another over an industrial control network along with thecontroller 118. For example, the control devices associated with eachelement may include a dedicated device controller (e.g., including aprocessor, memory, and control instructions), one or more actuators,valves, switches, and industrial control equipment, which enable controlbased on sensor feedback 130, control signals from the controller 118,control signals from a user, or any combination thereof. Thus, any ofthe control functionality described herein may be implemented withcontrol instructions stored and/or executable by the controller 118,dedicated device controllers associated with each element, or acombination thereof.

In order to facilitate such control functionality, the control system100 includes one or more sensors distributed throughout the system 10 toobtain the sensor feedback 130 for use in execution of the variouscontrols, e.g., the controls 124, 126, and 128. For example, the sensorfeedback 130 may be obtained from sensors distributed throughout theSEGR gas turbine system 52, the machinery 106, the EG processing system54, the steam turbine 104, the hydrocarbon production system 12, or anyother components throughout the turbine-based service system 14 or thehydrocarbon production system 12. For example, the sensor feedback 130may include temperature feedback, pressure feedback, flow rate feedback,flame temperature feedback, combustion dynamics feedback, intake oxidantcomposition feedback, intake fuel composition feedback, exhaustcomposition feedback, the output level of mechanical power 72, theoutput level of electrical power 74, the output quantity of the exhaustgas 42, 60, the output quantity or quality of the water 64, or anycombination thereof. For example, the sensor feedback 130 may include acomposition of the exhaust gas 42, 60 to facilitate stoichiometriccombustion in the SEGR gas turbine system 52. For example, the sensorfeedback 130 may include feedback from one or more intake oxidantsensors along an oxidant supply path of the oxidant 68, one or moreintake fuel sensors along a fuel supply path of the fuel 70, and one ormore exhaust emissions sensors disposed along the exhaust recirculationpath 110 and/or within the SEGR gas turbine system 52. The intakeoxidant sensors, intake fuel sensors, and exhaust emissions sensors mayinclude temperature sensors, pressure sensors, flow rate sensors, andcomposition sensors. The emissions sensors may includes sensors fornitrogen oxides (e.g., NO_(X) sensors), carbon oxides (e.g., CO sensorsand CO₂ sensors), sulfur oxides (e.g., SO_(X) sensors), hydrogen (e.g.,H₂ sensors), oxygen (e.g., O₂ sensors), unburnt hydrocarbons (e.g., HCsensors), or other products of incomplete combustion, or any combinationthereof.

Using this feedback 130, the control system 100 may adjust (e.g.,increase, decrease, or maintain) the intake flow of exhaust gas 66,oxidant 68, and/or fuel 70 into the SEGR gas turbine system 52 (amongother operational parameters) to maintain the equivalence ratio within asuitable range, e.g., between approximately 0.95 to approximately 1.05,between approximately 0.95 to approximately 1.0, between approximately1.0 to approximately 1.05, or substantially at 1.0. For example, thecontrol system 100 may analyze the feedback 130 to monitor the exhaustemissions (e.g., concentration levels of nitrogen oxides, carbon oxidessuch as CO and CO₂, sulfur oxides, hydrogen, oxygen, unburnthydrocarbons, and other products of incomplete combustion) and/ordetermine the equivalence ratio, and then control one or more componentsto adjust the exhaust emissions (e.g., concentration levels in theexhaust gas 42) and/or the equivalence ratio. The controlled componentsmay include any of the components illustrated and described withreference to the drawings, including but not limited to, valves alongthe supply paths for the oxidant 68, the fuel 70, and the exhaust gas66; an oxidant compressor, a fuel pump, or any components in the EGprocessing system 54; any components of the SEGR gas turbine system 52,or any combination thereof. The controlled components may adjust (e.g.,increase, decrease, or maintain) the flow rates, temperatures,pressures, or percentages (e.g., equivalence ratio) of the oxidant 68,the fuel 70, and the exhaust gas 66 that combust within the SEGR gasturbine system 52. The controlled components also may include one ormore gas treatment systems, such as catalyst units (e.g., oxidationcatalyst units), supplies for the catalyst units (e.g., oxidation fuel,heat, electricity, etc.), gas purification and/or separation units(e.g., solvent based separators, absorbers, flash tanks, etc.), andfiltration units. The gas treatment systems may help reduce variousexhaust emissions along the exhaust recirculation path 110, a vent path(e.g., exhausted into the atmosphere), or an extraction path to the EGsupply system 78.

In certain embodiments, the control system 100 may analyze the feedback130 and control one or more components to maintain or reduce emissionslevels (e.g., concentration levels in the exhaust gas 42, 60, 95) to atarget range, such as less than approximately 10, 20, 30, 40, 50, 100,200, 300, 400, 500, 1000, 2000, 3000, 4000, 5000, or 10000 parts permillion by volume (ppmv). These target ranges may be the same ordifferent for each of the exhaust emissions, e.g., concentration levelsof nitrogen oxides, carbon monoxide, sulfur oxides, hydrogen, oxygen,unburnt hydrocarbons, and other products of incomplete combustion. Forexample, depending on the equivalence ratio, the control system 100 mayselectively control exhaust emissions (e.g., concentration levels) ofoxidant (e.g., oxygen) within a target range of less than approximately10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 250, 500, 750, or 1000 ppmv;carbon monoxide (CO) within a target range of less than approximately20, 50, 100, 200, 500, 1000, 2500, or 5000 ppmv; and nitrogen oxides(NO_(X)) within a target range of less than approximately 50, 100, 200,300, 400, or 500 ppmv. In certain embodiments operating with asubstantially stoichiometric equivalence ratio, the control system 100may selectively control exhaust emissions (e.g., concentration levels)of oxidant (e.g., oxygen) within a target range of less thanapproximately 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 ppmv; andcarbon monoxide (CO) within a target range of less than approximately500, 1000, 2000, 3000, 4000, or 5000 ppmv. In certain embodimentsoperating with a fuel-lean equivalence ratio (e.g., betweenapproximately 0.95 to 1.0), the control system 100 may selectivelycontrol exhaust emissions (e.g., concentration levels) of oxidant (e.g.,oxygen) within a target range of less than approximately 500, 600, 700,800, 900, 1000, 1100, 1200, 1300, 1400, or 1500 ppmv; carbon monoxide(CO) within a target range of less than approximately 10, 20, 30, 40,50, 60, 70, 80, 90, 100, 150, or 200 ppmv; and nitrogen oxides (e.g.,NO_(X)) within a target range of less than approximately 50, 100, 150,200, 250, 300, 350, or 400 ppmv. The foregoing target ranges are merelyexamples, and are not intended to limit the scope of the disclosedembodiments.

The control system 100 also may be coupled to a local interface 132 anda remote interface 134. For example, the local interface 132 may includea computer workstation disposed on-site at the turbine-based servicesystem 14 and/or the hydrocarbon production system 12. In contrast, theremote interface 134 may include a computer workstation disposedoff-site from the turbine-based service system 14 and the hydrocarbonproduction system 12, such as through an internet connection. Theseinterfaces 132 and 134 facilitate monitoring and control of theturbine-based service system 14, such as through one or more graphicaldisplays of sensor feedback 130, operational parameters, and so forth.

Again, as noted above, the controller 118 includes a variety of controls124, 126, and 128 to facilitate control of the turbine-based servicesystem 14. The steam turbine control 124 may receive the sensor feedback130 and output control commands to facilitate operation of the steamturbine 104. For example, the steam turbine control 124 may receive thesensor feedback 130 from the HRSG 56, the machinery 106, temperature andpressure sensors along a path of the steam 62, temperature and pressuresensors along a path of the water 108, and various sensors indicative ofthe mechanical power 72 and the electrical power 74. Likewise, the SEGRgas turbine system control 126 may receive sensor feedback 130 from oneor more sensors disposed along the SEGR gas turbine system 52, themachinery 106, the EG processing system 54, or any combination thereof.For example, the sensor feedback 130 may be obtained from temperaturesensors, pressure sensors, clearance sensors, vibration sensors, flamesensors, fuel composition sensors, exhaust gas composition sensors, orany combination thereof, disposed within or external to the SEGR gasturbine system 52. Finally, the machinery control 128 may receive sensorfeedback 130 from various sensors associated with the mechanical power72 and the electrical power 74, as well as sensors disposed within themachinery 106. Each of these controls 124, 126, and 128 uses the sensorfeedback 130 to improve operation of the turbine-based service system14.

In the illustrated embodiment, the SEGR gas turbine system control 126may execute instructions to control the quantity and quality of theexhaust gas 42, 60, 95 in the EG processing system 54, the EG supplysystem 78, the hydrocarbon production system 12, and/or the othersystems 84. For example, the SEGR gas turbine system control 126 maymaintain a level of oxidant (e.g., oxygen) and/or unburnt fuel in theexhaust gas 60 below a threshold suitable for use with the exhaust gasinjection EOR system 112. In certain embodiments, the threshold levelsmay be less than 1, 2, 3, 4, or 5 percent of oxidant (e.g., oxygen)and/or unburnt fuel by volume of the exhaust gas 42, 60; or thethreshold levels of oxidant (e.g., oxygen) and/or unburnt fuel (andother exhaust emissions) may be less than approximately 10, 20, 30, 40,50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 1000, 2000, 3000, 4000, or5000 parts per million by volume (ppmv) in the exhaust gas 42, 60. Byfurther example, in order to achieve these low levels of oxidant (e.g.,oxygen) and/or unburnt fuel, the SEGR gas turbine system control 126 maymaintain an equivalence ratio for combustion in the SEGR gas turbinesystem 52 between approximately 0.95 and approximately 1.05. The SEGRgas turbine system control 126 also may control the EG extraction system80 and the EG treatment system 82 to maintain the temperature, pressure,flow rate, and gas composition of the exhaust gas 42, 60, 95 withinsuitable ranges for the exhaust gas injection EOR system 112, thepipeline 86, the storage tank 88, and the carbon sequestration system90. As discussed above, the EG treatment system 82 may be controlled topurify and/or separate the exhaust gas 42 into one or more gas streams95, such as the CO₂ rich, N₂ lean stream 96, the intermediateconcentration CO₂, N₂ stream 97, and the CO₂ lean, N₂ rich stream 98. Inaddition to controls for the exhaust gas 42, 60, and 95, the controls124, 126, and 128 may execute one or more instructions to maintain themechanical power 72 within a suitable power range, or maintain theelectrical power 74 within a suitable frequency and power range.

FIG. 3 is a diagram of embodiment of the system 10, further illustratingdetails of the SEGR gas turbine system 52 for use with the hydrocarbonproduction system 12 and/or other systems 84. In the illustratedembodiment, the SEGR gas turbine system 52 includes a gas turbine engine150 coupled to the EG processing system 54. The illustrated gas turbineengine 150 includes a compressor section 152, a combustor section 154,and an expander section or turbine section 156. The compressor section152 includes one or more exhaust gas compressors or compressor stages158, such as 1 to 20 stages of rotary compressor blades disposed in aseries arrangement. Likewise, the combustor section 154 includes one ormore combustors 160, such as 1 to 20 combustors 160 distributedcircumferentially about a rotational axis 162 of the SEGR gas turbinesystem 52. Furthermore, each combustor 160 may include one or more fuelnozzles 164 configured to inject the exhaust gas 66, the oxidant 68,and/or the fuel 70. For example, a head end portion 166 of eachcombustor 160 may house 1, 2, 3, 4, 5, 6, or more fuel nozzles 164,which may inject streams or mixtures of the exhaust gas 66, the oxidant68, and/or the fuel 70 into a combustion portion 168 (e.g., combustionchamber) of the combustor 160.

The fuel nozzles 164 may include any combination of premix fuel nozzles164 (e.g., configured to premix the oxidant 68 and fuel 70 forgeneration of an oxidant/fuel premix flame) and/or diffusion fuelnozzles 164 (e.g., configured to inject separate flows of the oxidant 68and fuel 70 for generation of an oxidant/fuel diffusion flame).Embodiments of the premix fuel nozzles 164 may include swirl vanes,mixing chambers, or other features to internally mix the oxidant 68 andfuel 70 within the nozzles 164, prior to injection and combustion in thecombustion chamber 168. The premix fuel nozzles 164 also may receive atleast some partially mixed oxidant 68 and fuel 70. In certainembodiments, each diffusion fuel nozzle 164 may isolate flows of theoxidant 68 and the fuel 70 until the point of injection, while alsoisolating flows of one or more diluents (e.g., the exhaust gas 66,steam, nitrogen, or another inert gas) until the point of injection. Inother embodiments, each diffusion fuel nozzle 164 may isolate flows ofthe oxidant 68 and the fuel 70 until the point of injection, whilepartially mixing one or more diluents (e.g., the exhaust gas 66, steam,nitrogen, or another inert gas) with the oxidant 68 and/or the fuel 70prior to the point of injection. In addition, one or more diluents(e.g., the exhaust gas 66, steam, nitrogen, or another inert gas) may beinjected into the combustor (e.g., into the hot products of combustion)either at or downstream from the combustion zone, thereby helping toreduce the temperature of the hot products of combustion and reduceemissions of NO_(X) (e.g., NO and NO₂). Regardless of the type of fuelnozzle 164, the SEGR gas turbine system 52 may be controlled to providesubstantially stoichiometric combustion of the oxidant 68 and fuel 70.

In diffusion combustion embodiments using the diffusion fuel nozzles164, the fuel 70 and oxidant 68 generally do not mix upstream from thediffusion flame, but rather the fuel 70 and oxidant 68 mix and reactdirectly at the flame surface and/or the flame surface exists at thelocation of mixing between the fuel 70 and oxidant 68. In particular,the fuel 70 and oxidant 68 separately approach the flame surface (ordiffusion boundary/interface), and then diffuse (e.g., via molecular andviscous diffusion) along the flame surface (or diffusionboundary/interface) to generate the diffusion flame. It is noteworthythat the fuel 70 and oxidant 68 may be at a substantially stoichiometricratio along this flame surface (or diffusion boundary/interface), whichmay result in a greater flame temperature (e.g., a peak flametemperature) along this flame surface. The stoichiometric fuel/oxidantratio generally results in a greater flame temperature (e.g., a peakflame temperature), as compared with a fuel-lean or fuel-richfuel/oxidant ratio. As a result, the diffusion flame may besubstantially more stable than a premix flame, because the diffusion offuel 70 and oxidant 68 helps to maintain a stoichiometric ratio (andgreater temperature) along the flame surface. Although greater flametemperatures can also lead to greater exhaust emissions, such as NO_(X)emissions, the disclosed embodiments use one or more diluents to helpcontrol the temperature and emissions while still avoiding any premixingof the fuel 70 and oxidant 68. For example, the disclosed embodimentsmay introduce one or more diluents separate from the fuel 70 and oxidant68 (e.g., after the point of combustion and/or downstream from thediffusion flame), thereby helping to reduce the temperature and reducethe emissions (e.g., NO_(X) emissions) produced by the diffusion flame.

In operation, as illustrated, the compressor section 152 receives andcompresses the exhaust gas 66 from the EG processing system 54, andoutputs a compressed exhaust gas 170 to each of the combustors 160 inthe combustor section 154. Upon combustion of the fuel 60, oxidant 68,and exhaust gas 170 within each combustor 160, additional exhaust gas orproducts of combustion 172 (i.e., combustion gas) is routed into theturbine section 156. Similar to the compressor section 152, the turbinesection 156 includes one or more turbines or turbine stages 174, whichmay include a series of rotary turbine blades. These turbine blades arethen driven by the products of combustion 172 generated in the combustorsection 154, thereby driving rotation of a shaft 176 coupled to themachinery 106. Again, the machinery 106 may include a variety ofequipment coupled to either end of the SEGR gas turbine system 52, suchas machinery 106, 178 coupled to the turbine section 156 and/ormachinery 106, 180 coupled to the compressor section 152. In certainembodiments, the machinery 106, 178, 180 may include one or moreelectrical generators, oxidant compressors for the oxidant 68, fuelpumps for the fuel 70, gear boxes, or additional drives (e.g. steamturbine 104, electrical motor, etc.) coupled to the SEGR gas turbinesystem 52. Non-limiting examples are discussed in further detail belowwith reference to TABLE 1. As illustrated, the turbine section 156outputs the exhaust gas 60 to recirculate along the exhaustrecirculation path 110 from an exhaust outlet 182 of the turbine section156 to an exhaust inlet 184 into the compressor section 152. Along theexhaust recirculation path 110, the exhaust gas 60 passes through the EGprocessing system 54 (e.g., the HRSG 56 and/or the EGR system 58) asdiscussed in detail above.

Again, each combustor 160 in the combustor section 154 receives, mixes,and stoichiometrically combusts the compressed exhaust gas 170, theoxidant 68, and the fuel 70 to produce the additional exhaust gas orproducts of combustion 172 to drive the turbine section 156. In certainembodiments, the oxidant 68 is compressed by an oxidant compressionsystem 186, such as a main oxidant compression (MOC) system (e.g., amain air compression (MAC) system) having one or more oxidantcompressors (MOCs). The oxidant compression system 186 includes anoxidant compressor 188 coupled to a drive 190. For example, the drive190 may include an electric motor, a combustion engine, or anycombination thereof. In certain embodiments, the drive 190 may be aturbine engine, such as the gas turbine engine 150. Accordingly, theoxidant compression system 186 may be an integral part of the machinery106. In other words, the compressor 188 may be directly or indirectlydriven by the mechanical power 72 supplied by the shaft 176 of the gasturbine engine 150. In such an embodiment, the drive 190 may beexcluded, because the compressor 188 relies on the power output from theturbine engine 150. However, in certain embodiments employing more thanone oxidant compressor is employed, a first oxidant compressor (e.g., alow pressure (LP) oxidant compressor) may be driven by the drive 190while the shaft 176 drives a second oxidant compressor (e.g., a highpressure (HP) oxidant compressor), or vice versa. For example, inanother embodiment, the HP MOC is driven by the drive 190 and the LPoxidant compressor is driven by the shaft 176. In the illustratedembodiment, the oxidant compression system 186 is separate from themachinery 106. In each of these embodiments, the compression system 186compresses and supplies the oxidant 68 to the fuel nozzles 164 and thecombustors 160. Accordingly, some or all of the machinery 106, 178, 180may be configured to increase the operational efficiency of thecompression system 186 (e.g., the compressor 188 and/or additionalcompressors).

The variety of components of the machinery 106, indicated by elementnumbers 106A, 106B, 106C, 106D, 106E, and 106F, may be disposed alongthe line of the shaft 176 and/or parallel to the line of the shaft 176in one or more series arrangements, parallel arrangements, or anycombination of series and parallel arrangements. For example, themachinery 106, 178, 180 (e.g., 106A through 106F) may include any seriesand/or parallel arrangement, in any order, of: one or more gearboxes(e.g., parallel shaft, epicyclic gearboxes), one or more compressors(e.g., oxidant compressors, booster compressors such as EG boostercompressors), one or more power generation units (e.g., electricalgenerators), one or more drives (e.g., steam turbine engines, electricalmotors), heat exchange units (e.g., direct or indirect heat exchangers),clutches, or any combination thereof. The compressors may include axialcompressors, radial or centrifugal compressors, or any combinationthereof, each having one or more compression stages. Regarding the heatexchangers, direct heat exchangers may include spray coolers (e.g.,spray intercoolers), which inject a liquid spray into a gas flow (e.g.,oxidant flow) for direct cooling of the gas flow. Indirect heatexchangers may include at least one wall (e.g., a shell and tube heatexchanger) separating first and second flows, such as a fluid flow(e.g., oxidant flow) separated from a coolant flow (e.g., water, air,refrigerant, or any other liquid or gas coolant), wherein the coolantflow transfers heat from the fluid flow without any direct contact.Examples of indirect heat exchangers include intercooler heat exchangersand heat recovery units, such as heat recovery steam generators. Theheat exchangers also may include heaters. As discussed in further detailbelow, each of these machinery components may be used in variouscombinations as indicated by the non-limiting examples set forth inTABLE 1.

Generally, the machinery 106, 178, 180 may be configured to increase theefficiency of the compression system 186 by, for example, adjustingoperational speeds of one or more oxidant compressors in the system 186,facilitating compression of the oxidant 68 through cooling, and/orextraction of surplus power. The disclosed embodiments are intended toinclude any and all permutations of the foregoing components in themachinery 106, 178, 180 in series and parallel arrangements, whereinone, more than one, all, or none of the components derive power from theshaft 176. As illustrated below, TABLE 1 depicts some non-limitingexamples of arrangements of the machinery 106, 178, 180 disposedproximate and/or coupled to the compressor and turbine sections 152,156.

TABLE 1 106A 106B 106C 106D 106E 106F MOC GEN MOC GBX GEN LP HP GEN MOCMOC HP GBX LP GEN MOC MOC MOC GBX GEN MOC HP GBX GEN LP MOC MOC MOC GBXGEN MOC GBX DRV DRV GBX LP HP GBX GEN MOC MOC DRV GBX HP LP GEN MOC MOCHP GBX LP GEN MOC CLR MOC HP GBX LP GBX GEN MOC CLR MOC HP GBX LP GENMOC HTR MOC STGN MOC GEN DRV MOC DRV GEN DRV MOC GEN DRV CLU MOC GEN DRVCLU MOC GBX GEN

As illustrated above in TABLE 1, a cooling unit is represented as CLR, aclutch is represented as CLU, a drive is represented by DRV, a gearboxis represented as GBX, a generator is represented by GEN, a heating unitis represented by HTR, a main oxidant compressor unit is represented byMOC, with low pressure and high pressure variants being represented asLP MOC and HP MOC, respectively, and a steam generator unit isrepresented as STGN. Although TABLE 1 illustrates the machinery 106,178, 180 in sequence toward the compressor section 152 or the turbinesection 156, TABLE 1 is also intended to cover the reverse sequence ofthe machinery 106, 178, 180. In TABLE 1, any cell including two or morecomponents is intended to cover a parallel arrangement of thecomponents. TABLE 1 is not intended to exclude any non-illustratedpermutations of the machinery 106, 178, 180. These components of themachinery 106, 178, 180 may enable feedback control of temperature,pressure, and flow rate of the oxidant 68 sent to the gas turbine engine150. As discussed in further detail below, the oxidant 68 and the fuel70 may be supplied to the gas turbine engine 150 at locationsspecifically selected to facilitate isolation and extraction of thecompressed exhaust gas 170 without any oxidant 68 or fuel 70 degradingthe quality of the exhaust gas 170.

The EG supply system 78, as illustrated in FIG. 3, is disposed betweenthe gas turbine engine 150 and the target systems (e.g., the hydrocarbonproduction system 12 and the other systems 84). In particular, the EGsupply system 78, e.g., the EG extraction system (EGES) 80), may becoupled to the gas turbine engine 150 at one or more extraction points76 along the compressor section 152, the combustor section 154, and/orthe turbine section 156. For example, the extraction points 76 may belocated between adjacent compressor stages, such as 2, 3, 4, 5, 6, 7, 8,9, or 10 interstage extraction points 76 between compressor stages. Eachof these interstage extraction points 76 provides a differenttemperature and pressure of the extracted exhaust gas 42. Similarly, theextraction points 76 may be located between adjacent turbine stages,such as 2, 3, 4, 5, 6, 7, 8, 9, or 10 interstage extraction points 76between turbine stages. Each of these interstage extraction points 76provides a different temperature and pressure of the extracted exhaustgas 42. By further example, the extraction points 76 may be located at amultitude of locations throughout the combustor section 154, which mayprovide different temperatures, pressures, flow rates, and gascompositions. Each of these extraction points 76 may include an EGextraction conduit, one or more valves, sensors, and controls, which maybe used to selectively control the flow of the extracted exhaust gas 42to the EG supply system 78.

The extracted exhaust gas 42, which is distributed by the EG supplysystem 78, has a controlled composition suitable for the target systems(e.g., the hydrocarbon production system 12 and the other systems 84).For example, at each of these extraction points 76, the exhaust gas 170may be substantially isolated from injection points (or flows) of theoxidant 68 and the fuel 70. In other words, the EG supply system 78 maybe specifically designed to extract the exhaust gas 170 from the gasturbine engine 150 without any added oxidant 68 or fuel 70. Furthermore,in view of the stoichiometric combustion in each of the combustors 160,the extracted exhaust gas 42 may be substantially free of oxygen andfuel. The EG supply system 78 may route the extracted exhaust gas 42directly or indirectly to the hydrocarbon production system 12 and/orother systems 84 for use in various processes, such as enhanced oilrecovery, carbon sequestration, storage, or transport to an offsitelocation. However, in certain embodiments, the EG supply system 78includes the EG treatment system (EGTS) 82 for further treatment of theexhaust gas 42, prior to use with the target systems. For example, theEG treatment system 82 may purify and/or separate the exhaust gas 42into one or more streams 95, such as the CO₂ rich, N₂ lean stream 96,the intermediate concentration CO₂, N₂ stream 97, and the CO₂ lean, N₂rich stream 98. These treated exhaust gas streams 95 may be usedindividually, or in any combination, with the hydrocarbon productionsystem 12 and the other systems 84 (e.g., the pipeline 86, the storagetank 88, and the carbon sequestration system 90).

Similar to the exhaust gas treatments performed in the EG supply system78, the EG processing system 54 may include a plurality of exhaust gas(EG) treatment components 192, such as indicated by element numbers 194,196, 198, 200, 202, 204, 206, 208, and 210. These EG treatmentcomponents 192 (e.g., 194 through 210) may be disposed along the exhaustrecirculation path 110 in one or more series arrangements, parallelarrangements, or any combination of series and parallel arrangements.For example, the EG treatment components 192 (e.g., 194 through 210) mayinclude any series and/or parallel arrangement, in any order, of: one ormore heat exchangers (e.g., heat recovery units such as heat recoverysteam generators, condensers, coolers, or heaters), catalyst systems(e.g., oxidation catalyst systems), particulate and/or water removalsystems (e.g., inertial separators, coalescing filters, waterimpermeable filters, and other filters), chemical injection systems,solvent based treatment systems (e.g., absorbers, flash tanks, etc.),carbon capture systems, gas separation systems, gas purificationsystems, and/or a solvent based treatment system, or any combinationthereof. In certain embodiments, the catalyst systems may include anoxidation catalyst, a carbon monoxide reduction catalyst, a nitrogenoxides reduction catalyst, an aluminum oxide, a zirconium oxide, asilicone oxide, a titanium oxide, a platinum oxide, a palladium oxide, acobalt oxide, or a mixed metal oxide, or a combination thereof. Thedisclosed embodiments are intended to include any and all permutationsof the foregoing components 192 in series and parallel arrangements. Asillustrated below, TABLE 2 depicts some non-limiting examples ofarrangements of the components 192 along the exhaust recirculation path110.

TABLE 2 194 196 198 200 202 204 206 208 210 CU HRU BB MRU PRU CU HRU HRUBB MRU PRU DIL CU HRSG HRSG BB MRU PRU OCU HRU OCU HRU OCU BB MRU PRUHRU HRU BB MRU PRU CU CU HRSG HRSG BB MRU PRU DIL OCU OCU OCU HRSG OCUHRSG OCU BB MRU PRU DIL OCU OCU OCU HRSG HRSG BB COND INER WFIL CFIL DILST ST OCU OCU BB COND INER FIL DIL HRSG HRSG ST ST OCU HRSG HRSG OCU BBMRU MRU PRU PRU ST ST HE WFIL INER FIL COND CFIL CU HRU HRU HRU BB MRUPRU PRU DIL COND COND COND HE INER FIL COND CFIL WFIL

As illustrated above in TABLE 2, a catalyst unit is represented by CU,an oxidation catalyst unit is represented by OCU, a booster blower isrepresented by BB, a heat exchanger is represented by HX, a heatrecovery unit is represented by HRU, a heat recovery steam generator isrepresented by HRSG, a condenser is represented by COND, a steam turbineis represented by ST, a particulate removal unit is represented by PRU,a moisture removal unit is represented by MRU, a filter is representedby FIL, a coalescing filter is represented by CFIL, a water impermeablefilter is represented by WFIL, an inertial separator is represented byINER, and a diluent supply system (e.g., steam, nitrogen, or other inertgas) is represented by DIL. Although TABLE 2 illustrates the components192 in sequence from the exhaust outlet 182 of the turbine section 156toward the exhaust inlet 184 of the compressor section 152, TABLE 2 isalso intended to cover the reverse sequence of the illustratedcomponents 192. In TABLE 2, any cell including two or more components isintended to cover an integrated unit with the components, a parallelarrangement of the components, or any combination thereof. Furthermore,in context of TABLE 2, the HRU, the HRSG, and the COND are examples ofthe HE; the HRSG is an example of the HRU; the COND, WFIL, and CFIL areexamples of the WRU; the INER, FIL, WFIL, and CFIL are examples of thePRU; and the WFIL and CFIL are examples of the FIL. Again, TABLE 2 isnot intended to exclude any non-illustrated permutations of thecomponents 192. In certain embodiments, the illustrated components 192(e.g., 194 through 210) may be partially or completed integrated withinthe HRSG 56, the EGR system 58, or any combination thereof. These EGtreatment components 192 may enable feedback control of temperature,pressure, flow rate, and gas composition, while also removing moistureand particulates from the exhaust gas 60. Furthermore, the treatedexhaust gas 60 may be extracted at one or more extraction points 76 foruse in the EG supply system 78 and/or recirculated to the exhaust inlet184 of the compressor section 152.

As the treated, recirculated exhaust gas 66 passes through thecompressor section 152, the SEGR gas turbine system 52 may bleed off aportion of the compressed exhaust gas along one or more lines 212 (e.g.,bleed conduits or bypass conduits). Each line 212 may route the exhaustgas into one or more heat exchangers 214 (e.g., cooling units), therebycooling the exhaust gas for recirculation back into the SEGR gas turbinesystem 52. For example, after passing through the heat exchanger 214, aportion of the cooled exhaust gas may be routed to the turbine section156 along line 212 for cooling and/or sealing of the turbine casing,turbine shrouds, bearings, and other components. In such an embodiment,the SEGR gas turbine system 52 does not route any oxidant 68 (or otherpotential contaminants) through the turbine section 156 for coolingand/or sealing purposes, and thus any leakage of the cooled exhaust gaswill not contaminate the hot products of combustion (e.g., workingexhaust gas) flowing through and driving the turbine stages of theturbine section 156. By further example, after passing through the heatexchanger 214, a portion of the cooled exhaust gas may be routed alongline 216 (e.g., return conduit) to an upstream compressor stage of thecompressor section 152, thereby improving the efficiency of compressionby the compressor section 152. In such an embodiment, the heat exchanger214 may be configured as an interstage cooling unit for the compressorsection 152. In this manner, the cooled exhaust gas helps to increasethe operational efficiency of the SEGR gas turbine system 52, whilesimultaneously helping to maintain the purity of the exhaust gas (e.g.,substantially free of oxidant and fuel).

FIG. 4 is a flow chart of an embodiment of an operational process 220 ofthe system 10 illustrated in FIGS. 1-3. In certain embodiments, theprocess 220 may be a computer implemented process, which accesses one ormore instructions stored on the memory 122 and executes the instructionson the processor 120 of the controller 118 shown in FIG. 2. For example,each step in the process 220 may include instructions executable by thecontroller 118 of the control system 100 described with reference toFIG. 2.

The process 220 may begin by initiating a startup mode of the SEGR gasturbine system 52 of FIGS. 1-3, as indicated by block 222. For example,the startup mode may involve a gradual ramp up of the SEGR gas turbinesystem 52 to maintain thermal gradients, vibration, and clearance (e.g.,between rotating and stationary parts) within acceptable thresholds. Forexample, during the startup mode 222, the process 220 may begin tosupply a compressed oxidant 68 to the combustors 160 and the fuelnozzles 164 of the combustor section 154, as indicated by block 224. Incertain embodiments, the compressed oxidant may include a compressedair, oxygen, oxygen-enriched air, oxygen-reduced air, oxygen-nitrogenmixtures, or any combination thereof. For example, the oxidant 68 may becompressed by the oxidant compression system 186 illustrated in FIG. 3.The process 220 also may begin to supply fuel to the combustors 160 andthe fuel nozzles 164 during the startup mode 222, as indicated by block226. During the startup mode 222, the process 220 also may begin tosupply exhaust gas (as available) to the combustors 160 and the fuelnozzles 164, as indicated by block 228. For example, the fuel nozzles164 may produce one or more diffusion flames, premix flames, or acombination of diffusion and premix flames. During the startup mode 222,the exhaust gas 60 being generated by the gas turbine engine 156 may beinsufficient or unstable in quantity and/or quality. Accordingly, duringthe startup mode, the process 220 may supply the exhaust gas 66 from oneor more storage units (e.g., storage tank 88), the pipeline 86, otherSEGR gas turbine systems 52, or other exhaust gas sources.

The process 220 may then combust a mixture of the compressed oxidant,fuel, and exhaust gas in the combustors 160 to produce hot combustiongas 172, as indicated by block 230. In particular, the process 220 maybe controlled by the control system 100 of FIG. 2 to facilitatestoichiometric combustion (e.g., stoichiometric diffusion combustion,premix combustion, or both) of the mixture in the combustors 160 of thecombustor section 154. However, during the startup mode 222, it may beparticularly difficult to maintain stoichiometric combustion of themixture (and thus low levels of oxidant and unburnt fuel may be presentin the hot combustion gas 172). As a result, in the startup mode 222,the hot combustion gas 172 may have greater amounts of residual oxidant68 and/or fuel 70 than during a steady state mode as discussed infurther detail below. For this reason, the process 220 may execute oneor more control instructions to reduce or eliminate the residual oxidant68 and/or fuel 70 in the hot combustion gas 172 during the startup mode.

The process 220 then drives the turbine section 156 with the hotcombustion gas 172, as indicated by block 232. For example, the hotcombustion gas 172 may drive one or more turbine stages 174 disposedwithin the turbine section 156. Downstream of the turbine section 156,the process 220 may treat the exhaust gas 60 from the final turbinestage 174, as indicated by block 234. For example, the exhaust gastreatment 234 may include filtration, catalytic reaction of any residualoxidant 68 and/or fuel 70, chemical treatment, heat recovery with theHRSG 56, and so forth. The process 220 may also recirculate at leastsome of the exhaust gas 60 back to the compressor section 152 of theSEGR gas turbine system 52, as indicated by block 236. For example, theexhaust gas recirculation 236 may involve passage through the exhaustrecirculation path 110 having the EG processing system 54 as illustratedin FIGS. 1-3.

In turn, the recirculated exhaust gas 66 may be compressed in thecompressor section 152, as indicated by block 238. For example, the SEGRgas turbine system 52 may sequentially compress the recirculated exhaustgas 66 in one or more compressor stages 158 of the compressor section152. Subsequently, the compressed exhaust gas 170 may be supplied to thecombustors 160 and fuel nozzles 164, as indicated by block 228. Steps230, 232, 234, 236, and 238 may then repeat, until the process 220eventually transitions to a steady state mode, as indicated by block240. Upon the transition 240, the process 220 may continue to performthe steps 224 through 238, but may also begin to extract the exhaust gas42 via the EG supply system 78, as indicated by block 242. For example,the exhaust gas 42 may be extracted from one or more extraction points76 along the compressor section 152, the combustor section 154, and theturbine section 156 as indicated in FIG. 3. In turn, the process 220 maysupply the extracted exhaust gas 42 from the EG supply system 78 to thehydrocarbon production system 12, as indicated by block 244. Thehydrocarbon production system 12 may then inject the exhaust gas 42 intothe earth 32 for enhanced oil recovery, as indicated by block 246. Forexample, the extracted exhaust gas 42 may be used by the exhaust gasinjection EOR system 112 of the EOR system 18 illustrated in FIGS. 1-3.

FIG. 5 is a schematic diagram of a portion of the gas turbine engine150. Elements in FIG. 5 in common with those shown in previous figuresare labeled with the same reference numerals. The axial direction of thegas turbine engine 150 is indicated by arrow 260, the radial directionis indicated by arrow 262, and the circumferential direction isindicated by arrow 264. These directions are all with respect to therotational axis 162. In the illustrated embodiment, an exhaust section266 is disposed downstream of the turbine section 156. The exhaustsection 266 may be used to expand and/or cool the exhaust gas 60 beforedirecting the exhaust gas 60 to the exhaust recirculation path 110.Specifically, a cross-sectional area of the exhaust section 266 mayincrease in the direction of the exhaust gas 60 flow, thereby increasingthe static pressure of the exhaust gas 60 by decreasing the kineticenergy of the exhaust gas 60. In the illustrated embodiment, a pluralityof sensor adaptor housings 268 (e.g., oxygen sensor adaptor housings)may be disposed in the turbine section 156 and the exhaust section 266.Each of the oxygen sensor adaptor housings 268 may include a sensor(e.g., an oxygen sensor) 270. In other words, the oxygen sensor 270 isdisposed within the oxygen sensor adaptor housing 268, which maysurround and protect the oxygen sensor 270 from the high temperatureswithin the gas turbine engine 150. Specifically, the sensor adaptorhousings 268 adapt a variety of sensors 270 to fit within the gasturbine engine 150, regardless of size or other characteristics of thesensor 270. In addition, each sensor adaptor housing 268 may include 1,2, 3, 4, 5, or more sensors 270, each of which may be the same ordifferent from one another. The plurality of oxygen sensor adaptorhousings 268 may be disposed at one or more axial 260 locations in theturbine section 156 and/or the exhaust section 266. In addition, theplurality of oxygen sensor adaptor housings 268 may be distributedradially 262 and/or circumferentially 264 throughout the turbine section156 and/or the exhaust section 266. In other embodiments, the pluralityof oxygen sensor adaptor housings 268 may be disposed in at least one ofthe combustor section 154, turbine section 156, or the exhaust section266, or any combination thereof. In various embodiments, the oxygensensor adaptor housings 268 may be disposed wherever oxygen sensorreadings may be desired throughout the gas turbine engine 150. Inparticular embodiments, it may be desirable to dispose the oxygen sensoradaptor housings 268 in the exhaust section 266 because of the lowertemperatures, pressures, and/or flow rates associated with the exhaustsection 266. As described in detail below, the oxygen sensor adaptorhousings 268 may maintain a temperature of a portion (e.g., portion notdirectly in contact with the combustion products) of the oxygen sensor270 below a threshold (e.g., a maximum operating temperature limit). Asshown in FIG. 5, the sensor feedback 130 from the plurality of oxygensensors 270 may be sent to the control system 100 to be used to adjustthe operation of the gas turbine engine 150. Specifically, the sensorfeedback 130 from the plurality of oxygen sensors 270 may be used by thecontrol system 100 to maintain the equivalence ratio of the gas turbineengine 150 within a range, such as a range between approximately between0.95 to approximately 1.05. In turn, this helps reduce residual oxygenin the exhaust gas, so that the exhaust gas is substantially or entirelyfree of oxygen.

FIG. 6 is a schematic diagram of an embodiment of the oxygen sensoradaptor housing 268 (e.g., one-piece or multi-piece cylindrical housing)coupled to a coolant supply system 280 that supplies a coolant 281 tothe oxygen sensor adaptor housing 268. As shown in FIG. 6, the oxygensensor adaptor housing 268 is disposed in an opening 282 formed in awall 284, which may correspond to a wall or other structure of thecombustor section 154, turbine section 156, or exhaust section 266. Theoxygen sensor adaptor housing 268 may be secured to the wall 284 via avariety of mounting techniques, such as, but not limited to, threadedconnections, bolted flanges, and so forth. The oxygen sensor adaptorhousing 268 may include an insertion portion 286 (e.g., immersivehousing) configured to extend a distance 288 radially 262 into a gasstream 290, which may correspond to any gas stream flowing through thecombustor section 154, turbine section 156, or exhaust section 266. Incertain embodiments, the distance 288 may be between approximately 35 cmto 65 cm, 40 cm to 60 cm, or 45 cm to 55 cm. In various embodiments, theoxygen sensor adaptor housing 268 may be recessed, flush, or protrudeinto the gas stream 290. Thus, the distance 288 may be zero, positive,or negative. An external portion 292 of the oxygen sensor adaptorhousing 268 may be disposed outside or external of the wall 284. Inother words, the insertion portion 286 may be exposed to hightemperatures associated with the gas stream 290, while the externalportion 292 may be exposed to ambient or near-ambient temperaturesoutside of the gas turbine engine 150.

As shown in FIG. 6, the coolant supply system 280 is coupled to theoxygen sensor adaptor housing 268. Specifically, the oxygen sensoradaptor housing 268 includes a coolant inlet 294 that conveys thecoolant 281 (e.g., gas and/or liquid coolant) to the oxygen sensoradaptor housing 268 and a coolant outlet 296 that conveys the coolant281 away from the oxygen sensor adaptor housing 268. In certainembodiments, the coolant 281 may include air, nitrogen, carbon dioxide,inert gas, refrigerant, or water, or any combination thereof. Moregenerally, the coolant supply system 280 may use any liquid coolantand/or gas coolant to help maintain the temperature of the portion(e.g., portion not directly in contact with the gas stream 290) of theoxygen sensor 270 below the threshold (e.g., a maximum operatingtemperature limit). In certain embodiments, the coolant supply system280 may be configured to supply the coolant 281 at a flow rate thatremoves heat from the oxygen sensor adaptor housing 268, such that thetemperature of the portion of the oxygen sensor 270 is maintained belowthe threshold. In other embodiments, the coolant 281 may be used tomaintain the temperature of the portion of the oxygen sensor 270 withina range (e.g., between upper and lower temperature thresholds). Forexample, in certain embodiments, the coolant supply system 280 maysupply air as the coolant 281 to the coolant inlet 294 at a flow ratebetween approximately 30 m³/hr to 105 m³/hr, 40 m³/hr to 95 m³/hr, or 50m³/hr to 85 m³/hr. In further embodiments, a portion of the coolant 281may enter (e.g., bleed) into the gas stream 290 via an opening in theoxygen sensor adaptor housing 268, which may be utilized when thecoolant 281 is compatible with the gas stream 290 (e.g., exhaust gascoolant).

As shown in FIG. 6, the coolant supply system 280 may include one ormore different components. For example, the coolant supply system 280may include a coolant supply pump 298 to provide the coolant 281 to thecoolant inlet 294. In further embodiments, a coolant supply valve 300may be used to adjust the flow rate of the coolant 281 to the coolantinlet 294. In other embodiments, a coolant cooler 302 (e.g., heatexchanger) may be used to cool the coolant 281 from the coolant outlet296 before returning the coolant 281 to the coolant inlet 294 foradditional cooling of the oxygen sensor 270. The coolant cooler 302 mayuse another coolant, such as water, refrigerant, air, and so forth, tocool the coolant 281. Thus, the various components of the coolant supplysystem 280 may be disposed along a coolant recirculation path 304. Inaddition, the control system 100 may generate one or more output signals306 to certain components of the coolant supply system 280, such as thecoolant supply pump 280 motor, coolant supply valve 300 actuator, and/orcoolant cooler 302 valve or fan motor. Specifically, the control system100 may use the output signals 306 to adjust the flow rate of thecoolant 281 flowing through the coolant recirculation path 304 to helpmaintain the temperature of the portion of the oxygen sensor 270 belowthe threshold. For example, the control system 100 may increase a speedof the coolant supply pump 298 motor, open the coolant supply valve 300via the actuator, and/or increase cooling supplied by the coolant cooler302 by opening a coolant valve or increase a fan speed if sensorfeedback 130 indicates that additional cooling of the oxygen sensor 270is desired. Alternatively, the control system 100 may be used if sensorfeedback 130 indicates that less cooling of the oxygen sensor 270 isdesired.

FIG. 7 is a radial cross-sectional view of an embodiment of the gasturbine engine 150 with a plurality of oxygen sensor adaptor housings268. Specifically, the plurality of oxygen sensor adaptor housings 268are disposed circumferentially 264 through the wall 284 of the combustorsection 154, turbine section 156, or exhaust section 266. Each of theplurality of oxygen sensor adaptor housings 268 may provide sensorfeedback 130 to the control system 100. By distributing the oxygensensor adaptor housings 268 circumferentially 264, the control system100 may be used to detect undesired radial 262 and/or circumferential264 distribution of the gas stream 290 (e.g., variations in the oxygenlevels) flowing within the wall 284. For example, this may help withcontrol of combustion and particularly with reducing residual oxygen andhelping to provide stoichiometric combustion. In certain embodiments,each of the plurality of oxygen sensor adaptor housings 268 may beseparated by a separation distance 320. In other words, the plurality ofoxygen sensor adaptor housings 268 may be distributed circumferentially264 in a uniform manner. In other embodiments, the plurality of oxygensensor adaptor housings 268 may be distributed circumferentially 264 ina non-uniform manner. For example, more of the plurality of oxygensensor adaptor housings 286 may be distributed along an upper portion ofthe wall 284 than a lower portion of the wall 284.

FIG. 8 is a perspective view of an embodiment of the oxygen sensor 270that may be disposed in embodiments of the oxygen sensor adaptor housing268. Specifically, the oxygen sensor 270 may include a sensor tip 330that may be configured to be exposed to the gas stream 290 duringoperation of the oxygen sensor 270. Thus, the sensor tip 330 may extendoutward from (e.g., beyond) the oxygen sensor adaptor housing 268. Thesensor tip 330 may have a maximum sustained operating temperature limitgreater than other portions of the oxygen sensor 270 and also greaterthan the temperature of the gas stream 290. For example, the maximumsustained operating temperature limit of the sensor tip 330 may begreater than or equal to approximately 500, 600, 700, 800, 900, 1000,1250, 1500, or greater degrees Celsius. Coupled to the sensor tip 330may be a hex section 332 that is configured to couple the oxygen sensor270 to the oxygen sensor adaptor housing 268, as described in detailbelow. As shown in FIG. 8, the hex section 332 (e.g., a tool-engageablehex portion) may include one or more threaded sections 334 (e.g., malethreads) and/or nuts 336 to couple the oxygen sensor 270 to an opening(e.g., threaded opening) formed in the oxygen sensor adaptor housing 268to enable the sensor tip 330 to extend into the gas stream 290. Forexample, the threaded section 334 may interface with a mating threadedsection (e.g., female threads) formed in the opening of the oxygensensor adaptor housing 268 and the nut 336 may be used to secure theoxygen sensor 270 against the oxygen sensor adaptor housing 268. Themaximum sustained operating temperature limit of the hex section 332 maybe less than that of the sensor tip 330. For example the maximumsustained operating temperature limit of the hex section 332 may beapproximately 500 degrees Celsius. Thus, the oxygen sensor adaptorhousing 268 may be configured to maintain the temperature of the hexsection 332 below the maximum sustained operating temperature limit ofthe hex section 332.

As shown in FIG. 8, the oxygen sensor 270 also includes a gland packing338, which may be coupled to the hex section 332. The gland packing 338may enclose the upper portion of the sensor tip 330 and serve as aninterface with wiring 340. As with the hex section 332, the maximumsustained operating temperature limits of the gland packing 338 and thewiring 340 may be less than that of the sensor tip 330. For example, themaximum sustained operating temperature limit of the gland packing 330may be approximately 200 degrees Celsius and the maximum sustainedoperating temperature limit of the wiring 340 may be approximately 150degrees Celsius. Thus, the oxygen sensor adaptor housing 268 may be usedto maintain the temperatures of the gland packing 338 and wiring 340below their respective maximum sustained operating temperature limits,as described in detail below. Specifically, the oxygen sensor adaptorhousing 268 may maintain the wiring 340 below approximately 125 degreesCelsius, 100 degrees Celsius, or 95 degrees Celsius. The wiring 340 maypass through and out of the oxygen sensor adaptor housing 268 beforecoupling to the control system 100 via a connector shell 342. Thus, thewiring 340 may be used to convey the sensor feedback 130 to the controlsystem 100. The maximum sustained operating temperature limit of theconnector shell 342 may be less than that of the sensor tip 330. Forexample, the maximum sustained operating temperature limit of theconnector shell 342 may be approximately 120 degrees Celsius. As theconnector shell 342 may be disposed outside of the gas turbine engine150, the connector shell 342 may not be expected to be exposed to thehigh temperatures associated with the gas stream 290, and may not becooled or protected by the oxygen sensor adaptor housing 268. In certainembodiments, the oxygen sensor 270 may be a wideband oxygen sensor, alambda oxygen sensor, an air/fuel meter, or a universal exhaust gasoxygen sensor (UEGO), or any combination thereof, as described infurther detail below.

FIG. 9 is a graph 360 of a signal characteristic curve of a widebandoxygen sensor or lambda oxygen sensor (e.g., sensor 270). As shown inFIG. 9, the graph 360 includes an x-axis 362 that represents lambda,which is the reciprocal of the equivalence ratio, or phi. As discussedabove, the equivalence ratio is the ratio of the actual fuel/oxidantratio relative to the stoichiometric fuel/oxidant ratio. Thus, lambda isthe ratio of the stoichiometric fuel/oxidant ratio relative to the ratioof the actual fuel/oxidant ratio. A lambda of greater than 1.0 resultsin a fuel-lean combustion of the fuel and oxidant whereas a lambda ofless than 1.0 results in a fuel-rich combustion of the fuel and oxidant.In contrast, a lambda of 1.0 results in combustion that is neitherfuel-rich nor fuel-lean, thereby substantially consuming all of the fueland the oxidant in the combustion reaction.

In FIG. 9, a y-axis 364 represents a pumping current of the oxygensensor 270. A wideband oxygen sensor may include an oxygen sensor celland a Nernst concentration cell separated by a diffusion gap throughwhich the gas stream 290 may diffuse into. An electronic circuitcontrols the pump flow through the oxygen pump cell in such a way thatthe composition of the gas in the diffusion gas remains constant with alambda of approximately one. This is measured by the Nernst cell. If thegas stream 290 is lean, the oxygen pump cell is activated to pump oxygenout the diffusion gap. If the gas stream 290 is rich, the direction offlow is reversed so that the cell pumps oxygen into the diffusion gap.The flow from the pump is proportional to the oxygen concentration inthe lean gas stream 290 or to the oxygen deficit in the rich gas stream290. Plotted on FIG. 9 is a sensor response curve 366 for the widebandoxygen sensor. As shown in FIG. 9, for values of lambda greater than one(e.g., positive), the pumping current is greater than zero and forlambda values less than one, the pumping current is less than zero(e.g., negative). As shown in FIG. 9 the signal response curve 366extends over a wide range of lambda values. In other words, the responseof the pumping current is gradual as the response curve 366 moves fromnegative to positive regions of the pumping current. Thus, small changesin the value of lambda may result in relatively small changes in thevalue of the pumping current. In contrast, narrowband oxygen sensors mayexhibit rapid or large changes in pumping current near values of lambdaof approximately one. As the value of lambda may be used by the controlsystem 100 to maintain stoichiometric operation of the gas turbineengine 150, wideband oxygen sensors may be well-suited for enablingcontrol of SEGR gas turbine systems 52. In other words, wideband lambdaoxygen sensors may provide accurate values of oxygen concentrationswhile narrowband oxygen sensors may typically be used to only indicate apresence or absence of oxygen at a particular concentration.

FIG. 10 is a side view of an embodiment of the oxygen sensor adaptorhousing 268. Elements in FIG. 10 in common with those shown in previousfigures are labeled with the same reference numerals. In the illustratedembodiment, the oxygen sensor adaptor housing 268 includes a firstconduit 380 (e.g., annular housing portion) and a second conduit 382(e.g., annular housing portion). The first conduit 380 includes thecoolant inlet 294 and the second conduit 382 includes the coolant outlet296. As shown in FIG. 10, the second conduit 382 at least partiallysurrounds (e.g., coaxial or concentric) the first conduit 380. The firstconduit 380 includes a first distal opening 386 though which the wiring340 extends. The second conduit 382 includes a second proximal opening384 through which the sensor tip 330 extends. In certain embodiments, asheath 388 surrounds the second conduit 382. The sheath 388 (e.g.,annular sheath) may include a mounting flange 390 (e.g., annularflange), which may be used to couple the oxygen sensor adaptor housing268 to the wall 284. For example, the mounting flange 390 may includebolt holes to receive bolts. In addition, the sheath 388 may helpprotect the outer portion 292 of the oxygen sensor adaptor housing 268.

FIG. 11 is a cross-sectional view of an embodiment of the oxygen sensoradaptor housing 268 of FIG. 10. The oxygen sensor adaptor housing 268includes a proximal end 400 and a distal end 402. As shown in FIG. 11,the wiring 340 enters the first conduit 380 through the first distalopening 386. The wiring extends through the first conduit 380 andcouples with the oxygen sensor 270 at least partially disposed in afirst proximal opening 404 of the first conduit 380. For example, thegland packing 338 of the oxygen sensor 270 may be disposed within thefirst proximal opening 404. A first inner diameter 406 of the firstconduit 380 may be greater than an oxygen sensor diameter 408, therebyenabling coolant 281 to flow adjacent the oxygen sensor 270 out throughthe first proximal opening 404. The oxygen sensor 270 may be disposed inthe second proximal opening 384. Specifically, the oxygen sensor may besealingly disposed in the second proximal opening 384, such that thecoolant 281 is blocked from flowing out of the second conduit throughthe second proximal opening 384 by the oxygen sensor 270. For example,the nut 336 of the hex region 332 may be used to secure the oxygensensor to the second conduit 382. Thus, the first and second conduits380 and 382 create coaxial or concentric passages, which enable the flowof the coolant 281 to reverse.

As shown in FIG. 11, the coolant 281 enters the first conduit 380through the coolant inlet 294 and flows toward the proximal end 400 asindicated by arrows 410. Thus, the coolant 281 flows adjacent the wiring340 and the portion of the oxygen sensor 270 disposed in the firstproximal opening 404, thereby providing forced convective cooling formaintaining the wiring 404 and the oxygen sensor 270 below thetemperature threshold, such as the maximum sustained operatingtemperature limits described above. At the proximal end 400, the coolant281 may change directions and move toward the distal end 402 asindicated by arrows 412. Specifically, the coolant 281 may move adjacentthe gland packing 338 and the hex region 332 before turning toward thedistal end 402 and moving through the interior of the second conduit382. As shown in FIG. 11, a second diameter 414 of the second conduit382 may be greater than the first diameter 406 of the first conduit 380.The coolant 281 may exit the second conduit 382 through the coolantoutlet 296. The coolant 281 flowing through the interior of the secondconduit 382 may further help maintain the temperature of the portion ofthe oxygen sensor 270 disposed within the oxygen sensor adaptor housing268 below the threshold temperature. Specifically, the coolant 281flowing through the second conduit 382 may provide a second barrier tothe high temperature of the gas stream 290 in addition to the firstbarrier provided by the coolant 281 flowing through the first conduit380. In addition, the coolant 281 may transfer heat from the gas stream290 away from the oxygen sensor 270 and oxygen sensor adaptor housing268. As shown in FIG. 11, the first conduit 380 is inserted through asecond distal opening 416 of the second conduit 382. In addition, thesecond conduit 382 may constitute the insertion portion 286 (e g,immersive housing).

FIG. 12 is a partial cutaway perspective view of an embodiment of theoxygen sensor adaptor housing 268. In the illustrated embodiment, theoxygen sensor adaptor housing 268 includes a distal cap 430 disposed atthe distal end 402 of the oxygen sensor adaptor housing 268. The distalcap 430 includes the coolant inlet 294, coolant outlet 296, and a wiringopening 432 through which the wiring 340 passes through. The distal cap430 is coupled to a proximal cap 434 disposed at the proximal end 400 ofthe oxygen sensor adaptor housing 268. The proximal cap 434 e.g.,annular cap) may include a flange 436 (e.g., annular flange) to enablethe proximal cap 434 to be coupled to the distal cap 430 (e.g., via boltholes). For example, a plurality of bolts may be used to couple thedistal cap 430 to the proximal cap 434. In other embodiments, theproximal cap 434 may be coupled to the distal cap 430 via a threadedconnection. The proximal cap 434 may include the insertion portion 286(e.g., immersive housing). In addition, the proximal cap 434 may includean oxygen sensor opening 438 through which the sensor tip 330 of theoxygen sensor 270 may extend therethrough. The flow of the coolant 281through the interior of the proximal cap 434 may help maintain thetemperature of the portions of the oxygen sensor 270 disposed in theinterior of the proximal cap 434 below the temperature thresholds ofthose portions of the oxygen sensor 270.

In certain embodiments, the oxygen sensor 270 may be mounted in theoxygen sensor adaptor housing 268 at an angle 440 from a longitudinalaxis of the gas turbine engine 150, which may be generally parallel tothe axial axis 260. In certain embodiments, the angle 440 may be greaterthan approximately 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50degrees, 60 degrees, 70 degrees, or 80 degrees. By positioning theoxygen sensor 270 at the angle 440, the sensor tip 330 may be orientedfacing the gas stream 290, which may improve the accuracy of readingsobtained by the oxygen sensor 270. In addition, by placing the oxygensensor 270 at the angle 440, any condensation or moisture that may formon the sensor tip 330 may be blown off the oxygen sensor 270 or fall offas a result of gravity. In other embodiments, the sensor tip 330 mayinclude a heater that maintains a tip temperature of the sensor tip 330within a temperature range, such as a temperature range above whichcondensation may form. In further embodiments, the oxygen sensor adaptorhousing 268 may include an access port 442 (e.g., a removable cover) toprovide access to the oxygen sensor 270. Specifically, by using theaccess port 442, the oxygen sensor 270 may be removed or repairedwithout disassembling the oxygen sensor adaptor housing 268, which maysimplify maintenance and/or reduce maintenance costs associated with thegas turbine engine 150. In certain embodiments, one or both of thedistal cap 430 and the proximal cap 434 may include a positioning key444 (e.g., protruding tab, pin, or panel) that orients the oxygen sensor270 facing upstream against the gas stream 290. For example, thepositioning key 444 may fit into a slot formed in the wall 284. In otherembodiments, the wall may include the positioning key and the oxygensensor adaptor housing 268 may include the slot. In further embodiments,the positioning key 444 may be used to position the sensor 270 in otherorientations, such as upstream, downstream, sideways, and so forth.

FIG. 13 is a partial cutaway perspective view of an embodiment of theoxygen sensor adaptor housing 268. In the illustrated embodiment, theoxygen sensor adaptor housing 268 may be disposed near the bottom of thegas turbine engine 150. Thus, the proximal end 400 is located above thedistal end 402. As shown in FIG. 13, the oxygen sensor 270 is disposedat the angle 440. Thus, the sensor tip 330 of the oxygen sensor 270points downward as with the oxygen sensor 270 shown in FIG. 12. Thus,any condensation that forms on the sensor tip 330 may drip off thesensor tip 330 as a result of gravity. In other respects, the oxygensensor adaptor housing 268 is similar to that shown in FIG. 12. Incertain embodiments, all of the oxygen sensors disposed in the pluralityof oxygen sensor adaptor housings 268 (e.g., the plurality of housings268 shown in FIG. 7) may be disposed at the angle 440 (e.g., pointed ina downward manner).

FIG. 14 is a partial cutaway perspective view of an embodiment of theoxygen sensor adaptor housing 268. A coolant pipe 460 may be coupled tothe coolant inlet 294 and disposed within the interior of the proximalcap 434. The coolant pipe 460 may terminate in a coolant nozzle 462configured to direct the coolant 281 toward the oxygen sensor 270,thereby helping to maintain the temperature of the portion of the oxygensensor 270 disposed within the interior of the proximal cap 434 belowthe temperature threshold. In certain embodiments, the oxygen sensoropening 438 may be located at the proximal end 400 of the proximal cap434. In other words, the oxygen sensor 270 may disposed at a value ofapproximately 90 degrees for the angle 440. In other respects, theembodiment of the oxygen sensor adaptor housing 268 shown in FIG. 14 issimilar to those shown in FIGS. 12 and 13.

FIG. 15 is a partial cutaway perspective view of an embodiment of theoxygen sensor adaptor housing 268. In the illustrated embodiment, thecoolant pipe 460 is coupled to the coolant inlet 294. In addition, acoolant coil 480 (e.g., a spiraling or helical coil of pipe) is coupledto the coolant pipe 460 and at least partially surrounds the oxygensensor 270, thereby maintaining the temperature of the portion of theoxygen sensor 270 disposed within the proximal cap 434 below thetemperature threshold. In other words, the flow of the coolant 281through the coil 480 may help maintain the temperature of the spacesurrounding the oxygen sensor 270 at a temperature below that of the gasstream 290. In other respects, the embodiment of the oxygen sensoradaptor housing 268 shown in FIG. 15 is similar to those shown inprevious figures.

FIG. 16 is a radial cross-sectional view of an embodiment of the oxygensensor adaptor housing 268 taken along the line labeled 16-16 in FIG.12. As shown in FIG. 16, the proximal cap 434 of the oxygen sensoradaptor housing 268 has a generally circular cross-sectional shape andthe wiring 340 may be generally located at the center of the proximalcap 434. As such, the wiring 340 is disposed far away from the gasstream 290, thereby helping to maintain the temperature of the wiring340 below the temperature threshold. In other embodiments, the proximalcap 434 may have other cross-sectional shapes, such as circular, oval,or airfoil-shaped cross-sectional shapes. In addition, although FIG. 16shows a cross-sectional view of the proximal cap 434, it is understoodthat FIG. 16 may also represent a radial cross-sectional view of thefirst conduit 380 shown in FIGS. 10 and 11.

FIG. 17 is a radial cross-sectional of an embodiment of the oxygensensor adaptor housing 268 taken along the line labeled 17-17 in FIG.12. In the illustrated embodiment, the proximal cap 434 has anairfoil-shaped cross-sectional shape. Such a cross-sectional shape forthe proximal cap 434 may reduce the resistance posed by the oxygensensor adaptor housing 268 to the gas stream 290, thereby reducing anypressure drop associated with the oxygen sensor adaptor housing 268. Asshown in FIG. 17, the wiring 340 is disposed toward the center of theproximal cap 434, thereby helping to maintain the temperature of thewiring 340 below the temperature threshold. As with the embodiment shownin FIG. 16, the cross-sectional shape shown in FIG. 17 may also apply tothe first conduit 380 shown in FIGS. 10 and 11. In addition, it shouldbe noted that features of all figures are intended to be used in any andall combinations with one another. For example, it is contemplated thatcertain embodiments may use all features of FIGS. 5 and 17 in a singleassembly.

As described above, certain embodiments of the gas turbine engine 150may include the combustor section 154 having the turbine combustor 160that generates combustion products, the turbine section 156 having oneor more turbine stages 174 driven by the combustion products, and anexhaust section 266 disposed downstream of the turbine section 156. Inaddition, the gas turbine engine 150 may include the oxygen sensoradaptor housing 268 disposed in at least one of the combustor section154, the turbine section 156, or the exhaust section 266, or anycombination thereof. In addition, the oxygen sensor 270 may be disposedin the oxygen sensor adaptor housing 268, which may help maintain thetemperature of the portion of the oxygen sensor 270 below thetemperature threshold. Specifically, the portion of the oxygen sensorthat is maintained below the threshold may be disposed within the oxygensensor adaptor housing 268. Thus, another portion of the oxygen sensor270, such as the sensor tip 330 may be disposed outside of the oxygensensor adaptor housing 268 and be exposed to the high temperaturesassociated with the gas stream 290. In certain embodiments, the coolant281 may flow through the interior of the oxygen sensor adaptor housing268 to help maintain the temperature of the portion of the oxygen sensor270 below the temperature of threshold, thereby extending the life ofthe oxygen sensor 270 and/or enabling the use of oxygen sensors 270 thatmay have maximum sustained operating temperature limits less than thetemperature of the gas stream 290, such as wideband oxygen sensors,lambda oxygen sensors, and/or UEGO oxygen sensors.

Additional Description

The present embodiments provide systems and methods for gas turbineengines. It should be noted that any one or a combination of thefeatures described above may be utilized in any suitable combination.Indeed, all permutations of such combinations are presentlycontemplated. By way of example, the following clauses are offered asfurther description of the present disclosure:

Embodiment 1. A system, comprising: a gas turbine engine, comprising: acombustor section having a turbine combustor that generates combustionproducts; a turbine section having one or more turbine stages driven bythe combustion products; an exhaust section disposed downstream of theturbine section; an oxygen sensor adaptor housing disposed in at leastone of the combustor section, the turbine section, or the exhaustsection, or any combination thereof; and an oxygen sensor disposed inthe oxygen sensor adaptor housing, wherein the oxygen sensor adaptorhousing is configured to maintain a temperature of a portion of theoxygen sensor below an upper threshold.

Embodiment 2. The system of embodiment 1, wherein the oxygen sensorcomprises at least one of a wideband oxygen sensor, a lambda sensor, anair/fuel meter, or a universal exhaust gas oxygen (UEGO) sensor, or anycombination thereof.

Embodiment 3. The system defined in any preceding embodiment, whereinthe portion of the oxygen sensor comprises at least one of a hexsection, a gland packing, wiring, or a connector shell, or anycombination thereof.

Embodiment 4. The system defined in any preceding embodiment, whereinthe oxygen sensor comprises a heater configured to maintain a tiptemperature of a tip portion of the oxygen sensor within a temperaturerange.

Embodiment 5. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises: a coolant inlet configuredto convey a coolant to the oxygen sensor adaptor housing to maintain thetemperature of the portion of the oxygen sensor below the upperthreshold; and a coolant outlet configured to convey the coolant awayfrom the oxygen sensor adaptor housing.

Embodiment 6. The system defined in any preceding embodiment, comprisinga coolant supply system configured to supply the coolant to the coolantinlet of the oxygen sensor adaptor housing.

Embodiment 7. The system defined in any preceding embodiment, whereinthe coolant comprises at least one of air, nitrogen, carbon dioxide,cooled exhaust gas, inert gas, or water, or any combination thereof.

Embodiment 8. The system defined in any preceding embodiment, whereinthe coolant supply system is configured to supply air to the coolantinlet at a flow rate between approximately 30 m³/hr to approximately 105m³/hr.

Embodiment 9. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises: a first conduit comprisinga first proximal opening, a first distal opening, and a first passage,wherein the coolant inlet is coupled to the first distal opening, theoxygen sensor is disposed at least partially within the first proximalopening, and the first passage is configured to convey the coolant fromthe distal opening, adjacent the oxygen sensor, and out through thefirst proximal opening; and a second conduit at least partiallysurrounding the first conduit and comprising a second proximal opening,a second distal opening, and a second passage, wherein the coolantoutlet is coupled to the second distal opening, the oxygen sensor issealingly disposed within the second proximal opening, and the secondpassage is configured to convey the coolant from adjacent the oxygensensor to the second distal opening.

Embodiment 10. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises: a distal cap, wherein thecoolant inlet and the coolant outlet are coupled to the distal cap; anda proximal cap, wherein the oxygen sensor is disposed in an oxygensensor opening of the proximal cap.

Embodiment 11. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises an access port configured toprovide access to the oxygen sensor.

Embodiment 12. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises at least one of a coolantnozzle configured to direct the coolant toward the oxygen sensor, or acoolant coil configured to convey the coolant from the coolant inlet tothe coolant outlet and configured to at least partially surround theoxygen sensor, or any combination thereof.

Embodiment 13. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises an immersive housing atleast partially disposed in a gas flow of at least one of the combustorsection, the turbine section, or the exhaust section, or any combinationthereof.

Embodiment 14. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises a positioning key configuredto orient the oxygen sensor facing upstream against a gas flow of atleast one of the combustor section, the turbine section, or the exhaustsection, or any combination thereof.

Embodiment 15. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing is configured to position the oxygensensor at an angle from a longitudinal axis of the gas turbine engine,wherein the angle is greater than approximately 10 degrees.

Embodiment 16. The system defined in any preceding embodiment,comprising a gas turbine engine controller configured to receive anoxygen signal from the oxygen sensor to maintain an equivalence ratio ofthe gas turbine engine within a range.

Embodiment 17. The system defined in any preceding embodiment, whereinthe range of the equivalence ratio is between approximately 0.95 toapproximately 1.05.

Embodiment 18. The system defined in any preceding embodiment, whereinthe gas turbine engine comprises an exhaust gas compressor driven by theturbine section, wherein the exhaust gas compressor is configured tocompress and route an exhaust gas to the turbine combustor.

Embodiment 19. The system defined in any preceding embodiment,comprising an exhaust gas extraction system coupled to the gas turbineengine, and a hydrocarbon production system coupled to the exhaust gasextraction system.

Embodiment 20. The system defined in any preceding embodiment, whereinthe gas turbine engine is a stoichiometric exhaust gas recirculation(SEGR) gas turbine engine.

Embodiment 21. The system defined in any preceding embodiment,comprising a plurality of oxygen sensor adaptor housings configured tomount circumferentially about at least one of the combustor section, theturbine section, or the exhaust section, or any combination thereof.

Embodiment 22. A system, comprising: an oxygen sensor adaptor housingconfigured to mount in at least one of a combustor section of a gasturbine engine, a turbine section of the gas turbine engine, or anexhaust section of the gas turbine engine, or any combination thereof;and an oxygen sensor disposed in the oxygen sensor adaptor housing,wherein the oxygen sensor adaptor housing is configured to maintain atemperature of a portion of the oxygen sensor below an upper threshold.

Embodiment 23. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises an insertion portionconfigured to extend a distance into a gas stream of at least one of thecombustor section, the turbine section, or the exhaust section, or anycombination thereof.

Embodiment 24. The system defined in any preceding embodiment, whereinthe distance is between approximately 35 cm to approximately 65 cm.

Embodiment 25. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises a circular, oval, orairfoil-shaped cross-sectional shape.

Embodiment 26. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises: a coolant inlet configuredto convey a coolant to the oxygen sensor adaptor housing to maintain thetemperature of the portion of the oxygen sensor below the upperthreshold; and a coolant outlet configured to convey the coolant awayfrom the oxygen sensor adaptor housing.

Embodiment 27. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises: a first conduit comprisinga first proximal opening, a first distal opening, and a first passage,wherein the coolant inlet is coupled to the first distal opening, theoxygen sensor is disposed at least partially within the first proximalopening, and the first passage is configured to convey the coolant fromthe distal opening, adjacent the oxygen sensor, and out through thefirst proximal opening; and a second conduit at least partiallysurrounding the first conduit and comprising a second proximal opening,a second distal opening, and a second passage, wherein the coolantoutlet is coupled to the second distal opening, the oxygen sensor issealingly disposed within the second proximal opening, and the secondpassage is configured to convey the coolant from adjacent the oxygensensor to the second distal opening.

Embodiment 28. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises: a distal cap, wherein thecoolant inlet and the coolant outlet are coupled to the distal cap; anda proximal cap, wherein the oxygen sensor is disposed in an oxygensensor opening of the proximal cap.

Embodiment 29. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises an access port configured toprovide access to the oxygen sensor.

Embodiment 30. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises at least one of a coolantnozzle configured to direct the coolant toward the oxygen sensor, or acoolant coil configured to convey the coolant from the coolant inlet tothe coolant outlet and at least partially surround the oxygen sensor, orany combination thereof.

Embodiment 31. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing comprises a positioning key configuredto orient the oxygen sensor facing upstream against a gas flow of atleast one of the combustor section, the turbine section, or the exhaustsection, or any combination thereof.

Embodiment 32. The system defined in any preceding embodiment, whereinthe oxygen sensor adaptor housing is configured to position the oxygensensor at an angle from a longitudinal axis of the gas turbine engine,wherein the angle is greater than approximately 10 degrees.

Embodiment 33. The system defined in any preceding embodiment, whereinthe portion of the oxygen sensor comprises at least one of a hexsection, a gland packing, wiring, or a connector shell, or anycombination thereof.

Embodiment 34. A method, comprising: combusting a fuel with an oxidantin a combustor section of a turbine combustor to generate combustionproducts; driving a turbine of a turbine section with the combustionproducts from the turbine combustor; expanding the combustion productsfrom the turbine through an exhaust passage in an exhaust section;sensing an oxygen concentration of the combustion products using anoxygen sensor disposed in an oxygen sensor adaptor housing that isdisposed in at least one of the combustor section, the turbine section,or the exhaust section, or any combination thereof; and maintaining atemperature of a portion of the oxygen sensor below an upper thresholdusing the oxygen sensor adaptor housing.

Embodiment 35. The method or system defined in any preceding embodiment,comprising combusting an exhaust gas with the fuel and the oxidant inthe combustor section.

Embodiment 36. The method or system defined in any preceding embodiment,wherein maintaining the temperature of the portion of the oxygen sensorbelow the upper threshold comprises cooling the portion of the oxygensensor using a coolant flowing through the oxygen sensor adaptorhousing.

Embodiment 37. The method or system defined in any preceding embodiment,comprising maintaining the temperature of the portion of the oxygensensor below approximately 95 degrees Celsius.

Embodiment 38. The method or system defined in any preceding embodiment,wherein the portion of the oxygen sensor comprises at least one of a hexsection, a gland packing, wiring, or a connector shell, or anycombination thereof.

Embodiment 39. The method or system defined in any preceding embodiment,comprising controlling an equivalence ratio of a gas turbine enginehaving the combustor section, the turbine section, and the exhaustsection within a range using a gas turbine engine controller configuredto receive an oxygen signal from the oxygen sensor.

Embodiment 40. The method or system defined in any preceding embodiment,wherein the range of the equivalence ratio is between approximately 0.95to approximately 1.05.

Embodiment 41. The method or system defined in any preceding embodiment,comprising maintaining a tip temperature of a tip portion of the oxygensensor within a temperature range using a heater of the oxygen sensor.

Embodiment 42. The method or system defined in any preceding embodiment,comprising: conveying a coolant to the oxygen sensor adaptor housingusing a coolant inlet of the oxygen sensor adaptor housing; andconveying the coolant away from the oxygen sensor adaptor housing usinga coolant outlet of the oxygen sensor adaptor housing.

Embodiment 43. The method or system defined in any preceding embodiment,comprising conveying the coolant from the coolant inlet to the coolantoutlet using a coolant coil at least partially surrounding the oxygensensor.

Embodiment 44. The method or system defined in any preceding embodiment,comprising: flowing a coolant through a first conduit of the oxygensensor adaptor housing; flowing the coolant adjacent the oxygen sensor,wherein the oxygen sensor is at least partially within a first proximalopening of the first conduit; flowing the coolant out of the firstproximal opening of the first conduit and into a second conduit at leastpartially surrounding the first conduit; and flowing the coolant throughthe second conduit and out of a second distal opening of the secondconduit.

Embodiment 45. The method or system defined in any preceding embodiment,comprising directing a coolant toward the oxygen sensor using a coolantnozzle of the oxygen sensor adaptor housing.

Embodiment 46. The method or system defined in any preceding embodiment,comprising disposing an immersive housing of the oxygen sensor adaptorhousing at least partially in a gas flow of at least one of thecombustor section, the turbine section, or the exhaust section, or anycombination thereof.

Embodiment 47. The method or system defined in any preceding embodiment,comprising orienting the oxygen sensor facing upstream against a gasflow of at least one of the combustor section, the turbine section, orthe exhaust section, or any combination thereof using a positioning keyof the oxygen sensor adaptor housing.

Embodiment 48. The method or system defined in any preceding embodiment,comprising positioning the oxygen sensor at an angle from a longitudinalaxis of the gas turbine engine using the oxygen sensor adaptor housing,wherein the angle is greater than approximately 10 degrees.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A system, comprising: a gas turbine engine, comprising: a combustorsection having a turbine combustor that generates combustion products; aturbine section having one or more turbine stages driven by thecombustion products; an exhaust section disposed downstream of theturbine section; an oxygen sensor adaptor housing disposed in at leastone of the combustor section, the turbine section, or the exhaustsection, or any combination thereof; and an oxygen sensor disposed inthe oxygen sensor adaptor housing, wherein the oxygen sensor adaptorhousing is configured to maintain a temperature of a portion of theoxygen sensor below an upper threshold.
 2. The system of claim 1,wherein the oxygen sensor comprises at least one of a wideband oxygensensor, a lambda sensor, an air/fuel meter, or a universal exhaust gasoxygen (UEGO) sensor, or any combination thereof.
 3. The system of claim1, wherein the portion of the oxygen sensor comprises at least one of ahex section, a gland packing, wiring, or a connector shell, or anycombination thereof.
 4. The system of claim 1, wherein the oxygen sensorcomprises a heater configured to maintain a tip temperature of a tipportion of the oxygen sensor within a temperature range.
 5. The systemof claim 1, wherein the oxygen sensor adaptor housing comprises: acoolant inlet configured to convey a coolant to the oxygen sensoradaptor housing to maintain the temperature of the portion of the oxygensensor below the upper threshold; and a coolant outlet configured toconvey the coolant away from the oxygen sensor adaptor housing.
 6. Thesystem of claim 5, wherein the oxygen sensor adaptor housing comprises:a first conduit comprising a first proximal opening, a first distalopening, and a first passage, wherein the coolant inlet is coupled tothe first distal opening, the oxygen sensor is disposed at leastpartially within the first proximal opening, and the first passage isconfigured to convey the coolant from the distal opening, adjacent theoxygen sensor, and out through the first proximal opening; and a secondconduit at least partially surrounding the first conduit and comprisinga second proximal opening, a second distal opening, and a secondpassage, wherein the coolant outlet is coupled to the second distalopening, the oxygen sensor is sealingly disposed within the secondproximal opening, and the second passage is configured to convey thecoolant from adjacent the oxygen sensor to the second distal opening. 7.The system of claim 5, wherein the oxygen sensor adaptor housingcomprises: a distal cap, wherein the coolant inlet and the coolantoutlet are coupled to the distal cap; and a proximal cap, wherein theoxygen sensor is disposed in an oxygen sensor opening of the proximalcap.
 8. The system of claim 1, wherein the oxygen sensor adaptor housingcomprises an access port configured to provide access to the oxygensensor.
 9. The system of claim 5, wherein the oxygen sensor adaptorhousing comprises at least one of a coolant nozzle configured to directthe coolant toward the oxygen sensor, or a coolant coil configured toconvey the coolant from the coolant inlet to the coolant outlet andconfigured to at least partially surround the oxygen sensor, or anycombination thereof.
 10. The system of claim 1, wherein the gas turbineengine comprises an exhaust gas compressor driven by the turbinesection, wherein the exhaust gas compressor is configured to compressand route an exhaust gas to the turbine combustor.
 11. The system ofclaim 10, comprising an exhaust gas extraction system coupled to the gasturbine engine, and a hydrocarbon production system coupled to theexhaust gas extraction system.
 12. The system of claim 10, wherein thegas turbine engine is a stoichiometric exhaust gas recirculation (SEGR)gas turbine engine.
 13. A system, comprising: an oxygen sensor adaptorhousing configured to mount in at least one of a combustor section of agas turbine engine, a turbine section of the gas turbine engine, or anexhaust section of the gas turbine engine, or any combination thereof;and an oxygen sensor disposed in the oxygen sensor adaptor housing,wherein the oxygen sensor adaptor housing is configured to maintain atemperature of a portion of the oxygen sensor below an upper threshold.14. The system of claim 13, wherein the oxygen sensor adaptor housingcomprises an insertion portion configured to extend a distance into agas stream of at least one of the combustor section, the turbinesection, or the exhaust section, or any combination thereof.
 15. Thesystem of claim 14, wherein the distance is between approximately 35 cmto approximately 65 cm.
 16. The system of claim 13, wherein the oxygensensor adaptor housing comprises a circular, oval, or airfoil-shapedcross-sectional shape.
 17. A method, comprising: combusting a fuel withan oxidant in a combustor section of a turbine combustor to generatecombustion products; driving a turbine of a turbine section with thecombustion products from the turbine combustor; expanding the combustionproducts from the turbine through an exhaust passage in an exhaustsection; sensing an oxygen concentration of the combustion productsusing an oxygen sensor disposed in an oxygen sensor adaptor housing thatis disposed in at least one of the combustor section, the turbinesection, or the exhaust section, or any combination thereof; andmaintaining a temperature of a portion of the oxygen sensor below anupper threshold using the oxygen sensor adaptor housing.
 18. The methodof claim 17, comprising maintaining the temperature of the portion ofthe oxygen sensor below approximately 95 degrees Celsius.
 19. The methodof claim 17, comprising controlling an equivalence ratio of a gasturbine engine having the combustor section, the turbine section, andthe exhaust section within a range using a gas turbine engine controllerconfigured to receive an oxygen signal from the oxygen sensor.
 20. Themethod of claim 19, wherein the range of the equivalence ratio isbetween approximately 0.95 to approximately 1.05.